For a very long time the UK has had a very peculiar approach to gambling. In the UK its more commonly known as betting.
In nearly every village, town and city you will find a betting outlet (called bookies in the UK) where you can walk in off the street and place bets every day of the week including the weekends. In fact every day that there is some sort of sporting event in the UK you will find these bookies open. There are quite a few main companies that provide this service - William Hill (probably the largest), Ladbrokes (maybe as big as William Hill), Coral, Paddy Power, Bet Fred and maybe one or two other high street bookies. The rest are online.
This industry was created off the back of horse racing, which dates back to at least the 18th century where land owners would wager money over which horse of theirs, compared to their nieghbours, was fastest over an informal course. In those days all the roads were unpaved and were therefore ripe for this sort of racing, though most races were across fields and over hedges (what today is called jump racing).
One of the oddest things that is unique to the UK (though I am not sure of other countries) is that betting is not a taxable activity as it is considered gambling and therefore any proceeds are gained tax-free.
Today you can bet on any sport in the world and on any game or match where there is a market created by the bookies.
Recently, there have been platforms created where you can become 'your own bookie' and provide the money (risk) to match a normal bet. This is done on betting exchanges. At the moment there are three main ones in the UK, the largest and best known of them being Betfair. The other two are Betdaq (owned by Ladbrokes) and Smarkets. The exchanges make their money by charging a percentage on any winnings - 5-10% on Betfair, 5% on Betdaq and 2% on Smarkets.
With all this comes some very interesting and little known quirks.
All companies allow you to have accounts where you can deposit monies and bet as little or as much as you want whenever you want with no minimum or maximum set for monies placed on bets, number of bets placed per day/month/year and only a minimum of £0 to have your account stay open. All for no monthly fees to have the account 'active'.
This effectively means that you can use the bookies as a sort of 'hidden' bank account. You can walk into any bookies in the country which you have an account with and withdraw any amount that you want. You can also go online and transfer any amounts to your bank account.
There are some reading this that will understand the import of what I have written - these are excellent means of holding cash without many people knowing about it.
Though there was a time where you could walk into a bookies and open an account without any ID, that is not possible today (May 2021). Its all to do with KYC (Know Your Customer) rules. But if one is smart about it, one could hide monies that one does not want others to see, like a spouse, the tax man, and other entities.