Which? analysis exposes UK mobile signal black spots; cities fare best

A new analysis by consumer watchdog Which? shows the quality of mobile connections can vary dramatically across the UK, with postcode districts in Wales and the South West among the worst and central urban areas among the most reliable.

Which? used real‑world data gathered from consumer mobile handsets to produce a percentage score for how consistently users experienced a “good” connection in each postcode district during the year to the end of August. The watchdog said the figures expose sharp local differences that national coverage claims can mask.

The worst performing postcode district was SA70, covering Tenby in Wales, where users reported a good connection just 54.3% of the time. Performance varied widely by operator: Three customers in SA70 experienced a good connection only 38% of the time, while EE and O2 customers scored 71% and 63% respectively. Which? ranked LD1 (Llandrindod Wells) second worst with an overall score of 54.8%, with Three again lowest at 41% and O2 highest at 66%.

Other low‑scoring areas included TA5 (Taunton) at 56.0% and several districts in Truro (TR4 at 57.8%, TR27 and TR18 also among the bottom 10). The watchdog highlighted pockets of patchy service across rural parts of Wales and the South West of England.

At the other end of the scale, central urban districts recorded the most consistent service. SE11 in London (Kennington and Vauxhall) and NG3 in Nottingham tied for the best score at 87.8%, with all four major networks—EE, O2, Three and Vodafone—delivering scores of 85% or higher in those districts. Other high‑ranking areas included Romford (RM5), Ilford (IG2), Watford (WD24), SW3 and SE27 in London, Glasgow’s G13, Bradford’s BD3 and Sutton’s SM3.

Which? said differences between operators in the same area were often significant, and choosing a provider that performs well locally can be the difference between seamless connectivity and frequent dropouts. Natalie Hitchens, Which? head of home products and services, said, "This research shows just how dramatically the quality of mobile coverage can vary across the UK. Choosing the right provider can mean the difference between seamless coverage or constantly battling to make a call from the comfort of your own home."

Which? made the underlying map available free to consumers so they can check the mobile quality in their postcode district and compare providers. The watchdog advised customers unhappy with their service to consult the map and consider changing provider when feasible.

Telecom operators typically advertise national coverage figures that describe geographic reach, but Which? emphasised its measure focused on the quality and consistency of connections experienced by users in everyday conditions. The dataset covered reported performance up to the end of August and reflected aggregated consumer handset measurements rather than operator‑reported infrastructure metrics.

The analysis underlines ongoing connectivity challenges in rural and coastal communities and suggests that national coverage percentages do not always translate into uniformly good service at postcode level. Urban areas, where mobile infrastructure is denser and traffic demand patterns differ, generally showed stronger and more consistent performance.

Which? did not recommend specific operators for all locations, noting that best performance depends on local factors. The watchdog encouraged consumers to use its mobile quality map to identify which network performs best in their immediate area before changing plans or committing to a new contract.

Mobile operators have been investing in network upgrades, including additional masts and spectrum, to improve capacity and coverage; however, Which?’s findings indicate that disparities remain across much of the country. The watchdog said the results should inform consumers and policy discussions about where future investment and regulatory attention are needed to reduce geographic gaps in mobile service quality.