Operating shortly after WWII (c1948) on, the Broadway Club in Bedford (30 miles N of London) had table games prior to official 'regulation' in the UK. A name change to the Priory Club brought two more denoms around 1950.
In those days, following regulation, an establishment would apply to a local magistrate for a gaming license, either 'unrestricted' or for specific occasions only. For a further 3 years this place continued to run under the belief a license had been issued. Apparently it had not and c1953 they were raided and closed down. To my knowledge no chips have previously been recorded.
These I have came from someone who actually gambled there at the time. He had them in his drawer for the past 53 years
Arguably these could be classified as 'illegals' although one could equally argue that any UK chips pre 1950 were from unlicensed premises anyway.
I only have a few chips (only 2 each of some) and I doubt any others exist. Strictly first come first served. Email me if interested. All prices include shipping:

2s6d Broadway - $30
5s Broadway - $15
10s Broadway - $20
£1 Broadway - $40
£5 Priory - $25
£10 Priory - $25

The pale gold hotstamps did not scan well but are almost perfect.