Anyone who has watched an email refuse to send somewhere past Port Talbot Parkway will not be surprised: for almost two-thirds of the train journey between Swansea and London, your mobile signal falls below the regulator’s minimum standard for usable internet.
The London–Swansea route ranks 18th of 24 UK rail journeys measured for mobile connectivity, according to analysis by business travel firm Good Business Travel — with what Ofcom defines as “good performance” for just 35% of the trip.
The analysis is based on Ofcom’s own connectivity-on-trains measurement study, which tested performance across all four major mobile networks.
And the firm found not a single UK train journey consistently meets the regulator’s 5Mbit/s benchmark for reliable internet.
Its most eye-catching claim: astronauts on the moon can achieve download speeds more than 100 times faster than that benchmark — making lunar internet comfortably quicker than anything available on a British train.
The worst route measured was Basingstoke to Coventry, with a reliable connection for just 6% of the journey, followed by Sheffield to Doncaster on 12% — around three minutes of usable signal.
Even the best performer, London Victoria to East Croydon, managed good performance for only 68% of the trip.
The Swansea line’s 35% puts it in the bottom third — behind London–Liverpool, London–Dover and London–Bristol, which topped the longer-distance routes at 43%.
With onboard wi-fi often patchy, most passengers fall back on mobile data — which is exactly what the study measured.
There are ways to improve your odds, according to the firm’s Natasha Inglis — starting with where you sit.
“Many people don’t realise that sitting on the side of the train facing nearby towns or major roads can improve your signal because you’re closer to mobile masts,” she said.
She also suggests switching your phone to 4G rather than letting it hunt for weak 5G signals, “which often makes connectivity even less reliable on moving trains”.
Satellite-enabled mobile services are beginning to roll out, she added, which could eventually cover the blackspots.
“Millions of people travel by train every week expecting to work, stream, message friends or simply stay connected,” she said. “Instead, they’re met with frozen video calls, emails that won’t send and endless buffering.”
Here is every route measured — ranked from worst connection to best:
| Rank | Route | Good performance (Ofcom) |
|---|---|---|
| 1 | Basingstoke – Coventry | 6% |
| 2 | Sheffield – Doncaster | 12% |
| 3 | Taunton – Leeds | 13% |
| 4 | London – Edinburgh | 14% |
| 5 | London – East Midlands Parkway | 14% |
| 6 | Bedford – London St Pancras (peak) | 15% |
| 7 | London – Manchester | 16% |
| 8 | London – Glasgow | 18% |
| 9 | London – Plymouth | 24% |
| 10 | London – Bournemouth | 25% |
| 11 | Derby – East Midlands Parkway | 26% |
| 12 | London – Edinburgh | 27% |
| 13 | Nottingham – East Midlands Parkway | 28% |
| 14 | Edinburgh – Inverness | 29% |
| 15 | Edinburgh – Glasgow | 30% |
| 16 | London – Leeds | 32% |
| 17 | London – Norwich | 32% |
| 18 | London – Swansea | 35% |
| 19 | London – Liverpool | 36% |
| 20 | London Bridge – Brighton | 37% |
| 21 | London – Dover | 40% |
| 22 | Liverpool – York | 40% |
| 23 | London – Bristol | 43% |
| 24 | London Victoria – East Croydon | 68% |
Improvements to Britain’s rail connectivity have been promised by the government — but for now, the moon remains better connected than the 10.28 to Paddington.
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