New speed test data found that the fastest urban area for broadband is Telford in Shropshire, but even here, average download speeds of 23Mbps still fall short of the super-fast minimum speed of 24Mbps.

The data – collected from broadband users in the 50 biggest UK cities and towns – shows that Belfast is the only capital city with average speeds above 20Mbps.

Even London is trailing behind what the Government classes as super-fast, with average download speeds of 17Mbps.

Shockingly, almost a fifth of broadband users in London (19%) are getting speeds of less than 3Mbps. It would take almost six hours to download a BluRay film at this speed, uSwitch said.

Although the average download speed across the whole of Britain has risen in recent years to 14.5Mbps, more than a quarter (27%) of postcodes suffer from sluggish speeds averaging less than 3Mbps.

In urban areas, Hull has made the least progress. In the past year, speeds there have increased by just 26% to 10.5Mbps.

In contrast, Leeds has seen speeds rocket by 87% since 2012. Further south, Norwich is also making fast progress, with speeds up 75% in just a year.

However, it is still one of the slowest UK cities for broadband, averaging 11.6Mbps. And its residents are still most likely to be struggling – over a third (35%) have not seen their average speeds break 3Mbps in the last 12 months, and neither have broadband users in Huddersfield and York.

Recent research from watchdog Ofcom revealed that superfast broadband is now available to almost two thirds of the country (65%).

However, too many consumers remain in the dark when it comes to upgrading to fibre, uSwitch said.

Only a quarter of consumers (25%) know they can get it. And price still remains a barrier with almost half (48%) of those who do not have it, saying it is too expensive.

Marie-Louise Abretti, telecoms expert at uSwitch.com, said: “Urban speeds in the UK are around three times faster than rural speeds, but even download speeds in Britain’s 50 biggest cities still aren’t super-fast.

“The Government’s blinkered focus on bringing super-fast connections to 95% of Britain by 2017 is all very well but, if they pull it off, it’s only half the battle won.

“If people don’t actually use super-fast broadband because it’s too expensive, or they don’t know they can get it, then what’s the point? Uptake will be heavily dependent on both price and awareness.”