The trick in the UK and other commenwealth nations like australia is that you can't get leverage on buying the actual stock, but instead you can use contracts-for-difference (CFD's) which are bets on stock prices. In the US you used to have bucket shops which operated on the same principle many decades ago.

Since we have stamp duty (a tax on share purchases), it is massively advantageous to use CFD's especially if you can find a provider who doesn't offer leverage, so your downside stays low. In addition since it is legally classed as gambling, earnings are not taxed which offers a nice tax advantage over stocks or options if you're investing more than £20k a year (the max you can invest tax-free a year in the UK in an ISA).