When a bunch of young traders on Reddit decided in January 2021 to go after leading hedge funds by pumping stocks such as GameStop and AMC, Wall Street shuddered as US armchair investors prompted wild market swings.

The traders benefiting from the huge surges in stocks that previously had been in the doldrums were sitting in their parents’ basements in the US, exchanging messages on social media. But wannabe traders in the UK fell behind, hampered by a lack of platforms that they could easily access.