I feel it's only fitting to start with the jetons as the £1 was made in April 1961 (along with the plaques) for the opening in May.
Le Cercle was one of the first casinos in London to get a licence (as far as I know) although it wouldn't surprise me if they (and others) had a gaming room long before the 1960 Betting act allowed casinos to operate (due to a loophole).

There were only a handful of the 3 lower values known until the "find" in 2019 and although they were made at different times, I class them as a set due to their similarity.
The £1s can suffer with/from deterioration and appear sunken although I expect it may be a combination of age, colour, chemical composition and size but many are still in perfect condition, even when in the same envelope that they were stored in for 27+ years.
I'm sorry to say that there are 4 or 5 people that have bought them from me and then resold with altered facts (hence inflating the prices and basically conning people) and I've tried my best to keep up with contacting all of the auction houses that fall for their tricks. My information hasn't always been heeded but nothing else I can do. I tried to let as many people as possible know the facts about them when I found them but I can't cover all bases.
I will put the other types up soon and will try to make it interesting and only mention trivia that isn't on the chip guide already.