I think this goes to show that any data collection is dangerous, even if government thinks they're the good guys (when in fact they're naively collecting data that could be weaponized against them very easily). The EU is on to it as well with MiFID II granular reporting of financial market transactions starting effectively next year.
Though I'm not sure the Brits are going to play along (where the majority of trading happens in Europe); after all, why should they go through the trouble of implementing MiFID/MiFIR when leaving EU anyway?
Edit: preventing insider trading