Point Topic prepared a map of UK broadband penetration.
City of London is at the top of the rankings with 210 total broadband lines for every 100 people. Westminster is some way behind with a broadband density of 22, and other prosperous London boroughs account for most of the top 10. Watford, Norwich and Southend are the only non-London local authorities in the top 10, and Cardiff is number 11, with 15 broadband lines per 100 people. At the other end of the scale, there are 12 local authorities where broadband density is less than 6. Besides the tiny Isles of Scilly, where broadband is virtually unavailable, six of them form the backbone of rural Wales (Powys, Ceredigion, Isle of Anglesey, Gwynedd, Carmarthenshire, Pembrokeshire), two are wilder areas of the South West (West Somerset, the Forest of Dean) and the others include the East Riding of Yorkshire and Berwick on Tweed on the Scottish border. Clearly remoteness and simple lack of broadband availability are the main reasons for low broadband density.