Is the 3UK Network Hopelessly Underdimensioned?

I arrived in London yesterday and as I already have a prepaid SIM from 3UK, I used it for Internet access. Interestingly, just like in the Italy roaming scenario with the same SIM, data rates in the evening around London Victoria station were less than 300 kbit/s. A rather unpleasant experience as web pages were loaded very slowly. So it looks like this is not only a roaming issue but the 3UK network as a whole seems to be currently aching under the load. If this is an issue on the cell level or if it is the core network equipment that is stretched beyond its limits in the evening hours is hard to tell from the outside. This morning, data rates are fine again, exceeding 1 MBit/s at the same location, i.e. also the same behavior as in the roaming scenario in Italy. I travel a lot and thus use lots of other 3.5G networks in Europe and I have never seen such a bad throughput anywhere before. Time to do something about it quickly before customers (including me) consider other options.