I said that only LCI use them, meaning the half dozen or so LCI owned casinos - Sportsmans, Golden Nugget, Cromwell, 50 St James etc.

All the Gala, Stanley and Grosvenor owned use chips. (Those that used to use tokens when they were still independent have ceased using them now)
Off the top of my head, all the 'private' ones use chips or dont have a £2.50 - Ritz, Les A, Napoleons etc.

So, only about a half dozen in use out of 30 odd London casinos. I was actually surprised to see them at the new place. I expected to see either a 50p chip or coinage. Considering they are only for the two £5 BJ tables and for £25 roulette even money payoffs I doubt they have more than a few hundred. Probably quite an expense for that few. They do appear to be real brass and not some cheap far east alloy
I think they are made by Malquoy? who are London based. I had some sample tokens from the gaming show and they look very similar in finish.