Waitrose seems to have a local beer - so there's Meantime - and you'd think the food halls of Selfridges or Fortnum and Mason would help. A couple of Camden Town ales and something new that I forget right now (will add later) in the former, and what I bought didn't have a bar code so led to all kinds of till chaos. Fortnum and Mason
So, off licenses. Yesterday I dropped into about twenty of them, or food and wine shops, and the selection is generally Hobgoblin, Badger, Newcastle Brown, Spitfire, Brakspear Oxford Gold and that's about it. Three food and wine shops in a row, exactly the same stock. Wines from all over the world, but no local beer. Last week I found a whole shop devoted to Adnams, but I've yet to find anything within, say, the Circle Line. More research is needed, but I know a lot of the brewers in London do sell bottles.
There's an old Time Out listing - but, again, none of these are central. Am I missing anywhere - aside from buying a take out at a pub itself (a Partizan, since you ask, but not one of these as it had citra hops and two others, and very nice, too).