Anecdotally, I've found that the UK doesn't have much brand loyalty as, say, Spain does where PS consoles always dominate Xbox (iirc).
PS1 was king, as was PS2. But these were the best consoles on offer at the time on account of their wide library and relatively cheap prices.
360 then hit the market and PS3 just didn't have anything to counter Gears in the early period. I know a few people who bought 360s just because they played Gears at a mate's place and it was totally unlike anything available on PS3. Of course, PS3 was cripplingly expensive at the time.
PS4 then corrected all the mistakes and is back on top.
The Wii was massively popular but, again, this was a flash in the pan. DS was also popular for a while but UK consumers seem to be quite fickle and will just buy whatever is popular or what their mate has.
I would also say, having lived on the continent for about 10 years, that the market conditions of the UK are more conducive to the UK seemingly having a larger share of the EU market than it otherwise might have. There are always crazy deals online for games and supermarkets, shops, CEX etc are all engaging in a constant price war which results in rapidly falling prices for new titles.
In Belgium, games were horrifically expensive everywhere and I was better off ordering from Amazon UK.
Again, though, this is all anecdotal. I could well be wrong.