Londoner here. These beers exist and are part of the historic English beer tradition but are few and far between in city pubs these days. Pubs have started to stock Radlers like Schofferhoffer which is my go to, or a half pint (284ml/~10oz) of a strong beer like IPA.
This. You used to be able to get a few "session ales" in pubs which were under 4% and meant for long drinking sessions, now because of the rise of craft beer you're lucky if you get one. Meanwhile, there's always a ton of options over 5.5% which used to be unheard of.
