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Slowest street in the UK? Really?
Tuesday 20 September 2011 14:59:12 by Andrew Ferguson

The ease with which an on-the-spot broadband speed test can be completed means that many users have tested their broadband connections speed using numerous web-based speed tests. Today a press release by uSwitch talks about the slowest fifty streets in the UK based on such data, confusing journalists and the public, based in part on the lack of clear information in the original release.

A number of news websites including The Guardian have mis-interpreted the 0.128Mb figure in the uSwitch report as 0.128 MegaBytes per second (MB/s), when it would appear to be 0.128 Megabits per second (Mb/s or Mbps). The original report should have been clearer and adopted a common notation such as 0.128Mbps (Megabits per second), i.e. show the full meaning in brackets the first time the units are used; missing off the time unit is a common shortening that pervades advertising and press releases for broadband. The average user struggles to understand the difference between a megabit and a megabyte, measurement units in a ratio of 1:8 apart (1MB/s or MegaByte per second = 8Mb/s Megabits per second).

One of the common ways of trying to explain what this means to users is to relate it to a 'real-world' example, however in this press release the company further confuses users by use of statistics which appear to, at least in our opinion, be questionable. It suggests that on these slowest connections, a movie would take 48 hours to download whilst a single music track would take 90 minutes. These numbers would equate to a movie being 2.7GB (Gigabytes) in size, although most standard definition movies manage between 1 to 1.5GB. Whilst this may be a perfectly valid point, it does warrant an explanation.

Getting the sums right

However what is more surprising is the discrepancy over the music track which based on their figures would have to be 90MB in size. Even taking an uncompressed CD-quality track, this would need to be 10 minutes in length, whereas most are shorter, and with common compression technologies such as MP3, most tracks are a fraction of this size, often around 5MB. At 0.134Mbps, a single 5MB MP3 single would take around 5 minutes to download. Even assuming the use high quality 160kbit/s (kilobits per second) encoding as used by the Apple iTunes service, the figures quoted by the compay are grossly over-estimated. Did they mean an album?

"Things are almost as bad on Forestfield, in the West Sussex town of Horsham, where the average broadband speed of just 0.134Mb again harks back to the Nineties. At that speed it may take up to a frustrating 90 minutes to download just one music track."

uSwitch Press Release

We have already seen evidence that broadband speeds are a factor which new home-buyers take into consideration when looking to purchase a property, so home owners on the streets labelled the UK's slowest may be concerned about how these types of results may put off potential buyers. The press release does not offer any detail on the statistiscal accuracy or sample size of the data at street-level, making the analysis at best, incomplete. If the results are based on repeated tests from a couple of properties for example, this could be grossly under-estimating speeds for the entire road, as speed issues could be caused by traffic shaping, selection of broadband package, wireless interference or problems with telephone wiring inside the homes. The use of 'mean' averages for this kind of statistic is perhaps also questionable, where medians or percentiles tell a fuller story. The company compares its results to the May 2011 Ofcom research, but surprisingly does not provide a UK-wide average of its data in the press release.

If we look more closely at the slowest street in the entire UK based on this data (Mount Pleasant in Hasleworth, Suffolk), this is less than 300 metres away from the telephone exhange based on uSwitch's own data and a nearby result 380 metres away is 5.9Mbps—We would very much like to see why the speed variation is so large if uSwitch believe this is the slowest street in the country.

Screenshot of test result nearby to the UK's slowest street; Source:;
Map data by Google Maps/Tele Atlas.

We agree there is a problem with broadband speeds which warrants discussion and debate and using case studies is helpful to translate this into plain english, but highlighting the 'worst 50 broadband streets' is often prone to problems as the data set is unlikely to be complete enough, even though they attract many headlines. We have already seen users contacting us some months ago to complain about their village being labelled as one of the slowest in Britain based on this type of press release, whilst excluding niche broadband providers which offer much faster services from the data set. When focussing on trying to name very small areas, in-depth analysis is very important. Average speeds tell us a story about the development of UK broadband, but they are difficult to compare statistically at street-level when reducing the figure to a single number. The range of speeds, providers and other information is essential before making judgements about an area.

We contacted uSwitch to seek clarification on the units, calculation methodology and statistical significance and received the following response:

"Firstly, we are referring to MB/s (Mbps) in the release. We use the shortened terminology as widely used by the UK's most popular ISPs. As for the calculations, the data is based on more than 1,500,000 speed tests were conducted through the website between March and August 2011. The reason the map may have different results is because we do not show all results on the map - just the most recent tests for each postcode. However, all tests are logged, which is why we have such extensive data. The calculations are based on a uSwitch methodology, which uses our own data."

Statement by

We're honestly not quite sure what to make of it. If this is the case, their figures are even more implausible. We'll try to seek further clarification and will of course update the article in due course.

Disclosure: We feel it is appropriate to highlight to readers that thinkbroadband collects and analyses speed test data of its own and therefore we are generally reluctant to openly criticise methodologies/analysis used by other sites which carry out similar functions, after all, it is in the consumers' interests to access such analysis from multiple sources. However, due to the number of significant concerns we have raised about this release and the fact it has already been covered in the national media, we believe that it is in the public interest for us to make our concerns known.


Posted by weesteev over 5 years ago
Typical media crap about speed test results which rely inherently on customers testing themselves. Until all ISP's can put a system in place to speed test their own connections using gear like the SamKnows hub then these press releases wont be worth the paper they are written on. Otherwise, really good post Andrew :)
Posted by m0aur over 5 years ago
I get 12mb from Plusnet at the opposite end of our village to the exchange, while some next to the exchange get half that with BT. Red spot=exchange.
Posted by m0aur over 5 years ago
Probably the direct link shows a better breakdown.!lat=52.10229799999999&lng=0.6705249999999863&zoom=15&type=terrain&exchanges&speed-cluster
Posted by seb (Favicon staff member) over 5 years ago
@weesteev: We don't see any problems with the testing uSwitch does per se; The issue we have is how they have turned that into claims about slowest streets. Samknows couldn't really do that any better with their methodology, but at least Ofcom don't go making such claims.

m0aur: We are intentionally NOT comparing uSwitch results to ours as that could open up even more issues and then it's not about accuracy but about interpretation. We believe their claims don't stand up to scrutiny based on their own PR (e.g. download times).
Posted by themanstan over 5 years ago
m0aur, you've likely been sensible and gone for PLusNet LLU which puts you on ADSL2+, whilst those next to the exchange are likely on BTs prehistoric ADSL1 equipment so 6mb is about as fast as you can get from that technology. And they haven't changed BB supplier through apathy.
Posted by andrew (Favicon staff member) over 5 years ago
Plusnet does not do LLU, it uses the ADSL or ADSL2+ supplied by BT Wholesale which is also what BT Retail use.

Posted by herdwick over 5 years ago
uSwitch are charlatans - go look at their website and see what options you have. You'll find a few ISPs that pay uSwitch handsome commissions and that's it.
Posted by themanstan over 5 years ago
So you're saying m0aur uses BT wholesale project and so do his fellow villagers. He's ADSL2+ (clearly), they are on an ADSL1 product or have terrible lines or have the worst extensions in the world killing their connection speeds...
Posted by cyberdoyle over 5 years ago
another megabucket for guardian reporter Juliet Garsdale - it is megabit per second not megabyte. luv.

Ha, I see the Guardian has changed its website to megabits now. We awarded them a megabucket this morning.
Posted by seb (Favicon staff member) over 5 years ago
@cyberdoyle: It's a common mistake journos make.. they aren't broadband journos so it's understandable from time to time.. Guardian still saying 90 mins for a music track though which is just not right.
Posted by warweezil over 5 years ago
The street highlighted in Haverfordwest is only around a mile and a half from the exchange. The BTw line checker suggests around 5 Mbps for that post code. I guess this figure is skewed by one address with problems.

Clearly the figures are not reliable. someone 2 streets away from me gets 0.8Mbps compared to the 5 Mbps I get from my line which no longer has extensions and a router resited away from an external noise source. So another worthless report from a company that hasnt done the legwork.
Posted by Somerset over 5 years ago
m0aur - I get 12mb from Plusnet.

12 milli bits per day/week???

Posted by m0aur over 5 years ago
Yes, good speed wit Plusnet. The link I posted shows what I was getting with the Post Office till 3 weeks ago. No LLU on Eagle. I am 2.3km from the exchange as computed by my noise and attenuation, so I don't know what those nect to the exchange are doing, but it must be something they are, or are not doing. It just shows that most of the complaints are just hot air from those that don't know what is what.
Posted by m0aur over 5 years ago
Sometimes more!!!!
Posted by GeeTee over 5 years ago
You really couldn't make it up. I love the clarification...

"Firstly, we are referring to MB/s (Mbps) in the release. /snip"

Pure genius :D
Posted by jchevali over 5 years ago
Very good article - rightly critical and highly relevant.
Posted by GloryHornet over 5 years ago
The speed tests, don't tally up with thinkbroadbands they were telling me I had a 6mb download when my router is only connected at 5.3?? Plus there "recommendation to me is to get Sky Unlimited and that isn't even available in my area.
Posted by seb (Favicon staff member) over 5 years ago
@warweezil: The figures are useful.. Yes we have a slightly different measurement methodology.. the issue we have is trying to claim you can use it to say 'these are the slowest streets in the UK' when there's just not enough data. We're very careful with the claims we make on our data for this very reason. There are many reasons for speed problems, so hence why you can't take a small sample (which inevitably you will have at street-level)
Posted by warweezil over 5 years ago
I could have been clearer, the figures as used are unreliable as a benchmark to illustrate low speeds in an area especially as they ignore other speeds in the same estate (Its Ex MOD housing) that include 1 BT retail test at 5.2 Mbps (for this check I used postcode SA61 1HQ)

Posted by warweezil over 5 years ago
It is pretty much the same as where I am, and locally there are huge variations. I have tried their tester, and it seems... ummm "optimistic" at times, unlike the Thinkbroadband test which over the years I have been using it has shown itself to be a very good indicator of the true speed when compared against the BTw tester (when it used to work on my line).

I have a line that normally returns around 5Mbps, there are others round here that show up on other maps that record far slower speeds - even those closer to our local cab.
Posted by m0aur over 5 years ago
The main difference between TBB speed-tests and others, is that TBB reports the average speed for the test, where many others report the highest peak achieved.
Posted by Somerset over 5 years ago
Wiring, wiring, wiring.
Posted by alwall over 5 years ago
But....which is the slowest street in the UK?
Posted by creakycopperline over 5 years ago
5.9 mb is slow? mine is 5 and it's considered good speed
Posted by GMAN99 over 5 years ago
I'm on 3.7, 5 is a dream :)
Posted by TheGuv over 5 years ago
uSwitch are publicity seeking frauds. They will put up the front that they are helping consumers but they are not government accredited because their primary aim is to benefit themselves.

I'd rather see all comparison website be forced to meet strict standards so they stop promoting companies that pay them bugger royalties.

I don't really buy into the idea that these streets are overly slow and believe that the tests are probably flawed.
Posted by mervl over 5 years ago
It's pretty clear really: U-switch state what they've concluded from data they've chosen using their methodology! I (or anyone else) might find a result that's worse. A competition to see how low you can go, perhaps?
Posted by kp52 over 5 years ago
Does "1MB/s or MegaByte per second = 8Mb/s Megabits per second" on aan ADSL line? I know we don't have the good old start and stop bits that meant you need at least ten bits of signalling to send one byte of data, but don't all those bits of packet framing etc. information mean that 8Mb/s is less than 1MB/s? And if we're talking clarity, how about 128kbps (kilobits per second)rather than 0.128Mbps?
Posted by andrew (Favicon staff member) over 5 years ago

An 8128Kbps sync will manage around 7100-7200Kbps of IP throughput after all the overheads.

But as they are talking about speedtest and file downloads, the simple 8 bits in a byte applies, i.e. all the talk is at the IP layer.
Posted by otester over 5 years ago

5.9Mbps with a 380m line is pretty slow, your expecting at least 7/20Mbps (ADSL1/ADSL2+).

Also 90MB may have been album size and 2.7GB isn't unusual, since you have 720p movies (2-5GB) and 1080p (6-15GB).
Posted by andrew (Favicon staff member) over 5 years ago
Their press release (go read it) did not say album, and it simply said HD film, no indication of quality/size. Omissions by them, it is normal to include these information in the footnotes for journalists.

720p yes maybe, but as at least two common movie services use 1080p for their HD, many will presume that is what is meant. I have MP3 tracks that are 90MB in size, but are one hour long remix affairs.
Posted by otester over 5 years ago

I was thinking more along the lines of "unofficial distribution channels" (aka the more popular ones).
Posted by IvahOB over 5 years ago
I can't believe we are not bottom of table. Just used test on this site at 0.9/0.4 Mbps. Will never get better without B4RN!
Posted by camieabz over 5 years ago
"It's a common mistake journos make.. they aren't broadband journos so it's understandable from time to time.."

I'm afraid I can't agree. 'Journos' are supposed to research their stories, gather info, interview specialists if necessary.

Wouldn't want them mis-reporting the radiation readings at Fukushima. :)
Posted by herdwick over 5 years ago
Hear hear, if you don't understand it don't write about it.
Posted by seb (Favicon staff member) over 5 years ago
@TheGuv: We aren't "accredited" by anyone and I don't think more regulation would be helpful. In the end, we're happy to stand on our own merit. (we have our own problems.. we're not perfect!)
Posted by stduc over 5 years ago
Try the Farnham Royal Exchange my Dad gets 0.024Mbps on a good day - and yes you read correctly - only half dial up speed.
Posted by veryslowlyslowly over 5 years ago
In my area Bt is a disaster so I use 3G, where speed is not the whole story, surely drop outs and lock ups puts 3G worst of the worst pile :(
Posted by otester over 5 years ago

ISP? Line length? Attenuation?


BT Retail isn't the only ISP available through BT Wholesale.
Posted by AspieMum over 5 years ago
I wish I was only 380 meters from my exchange. I am 1.7 miles away from my exchange according to USwitch. On the Thinkbroadband speed test I did earlier I had downstream of 1719 Kbps and upstream of 644 Kbps and it says my speed is 1.7 Mbps. I can't even use broadband using a dongle or such like- that sort is not available (mobile connection is too poor). If I was 380 meters away...
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