Do we have a date of UK implementation for the change in regulation that brought about a 25-year retention period for CTIMPs?

Presumably, trials that submitted their end of trial notification prior to the change in regs will continue/default to the previous 15-year retention period?

I fear Brexit has muddied the waters, due to the delays in the exit date and EU implementation of this... I believe it all stems from EU Reg 2014/536

Thank you in anticipation