I tested in Birmingham Airport and city centre, Glasgow Airport and city centre and the train between Birmingham and Leamington Spa. The train I can understand - it's a Faraday cage of sorts and it's moving at speed. But the airports and city centres are supposed to have the best coverage and I got an average of 6KB/s (min:4 /max:8) download speeds.
That's strange, I've seen broadband like speeds in some of those places.