https://www.legislation.gov.uk/uksi/2021/10/contents/made
Looks like the first changes post EASA exit have just been made – reintroduces the U.K. Class D VFR limits SERA exemption into law from May, removes drone pilot minimum age limits and makes the Personal Medical Declaration use permanent! This is a massive move and on my first reading of the text it seems to be for PPL and LAPL privileges (not just LAPL level as before). I’m sure a CAA announcement will clarify soon, but this is a big step for U.K. GA.
Is the PMD now (again) usable for Part 23 (certified) aircraft? That would be amazing.
Yes – Part-21 G reg aircraft in U.K. airspace
The existing PMD derogation can already by used at Night as that is part of LAPL privileges. If I read this correctly this is PPL and LAPL, but I can’t see it is restricted to LAPL privileges (but we may only be seeing part of the implementation). If so, that could potentially be anything attached to a PPL.
The revised rule comes into force on 28 Jan 2021.
MED.A.030(c)(2) When exercising the privileges of a private pilot
licence (PPL), the pilot shall hold at least a valid class 2 medical
certificate (except where the pilot is exercising the privileges of a
LAPL in respect of aircraft other than turbine engine helicopters, in
which case the pilot shall hold at least a valid class 2 medical
certificate or have made a medical declaration).
Ah yes I’ve reread and see how it comes together now. Excellent result, so operate a PPL as LAPL which can permit day and night VFR. Brilliant news
What is LAPL?
Light Aircraf Pilot License, a sub-ICAO invention of EASA.
It’s a curious way to specify privileges. It’s like saying you can operate the privileges of a US Private Certificate with the pilot having just one eye and one leg 
(actually they would be the same but you get my drift).
Limiting the PPL+PMD operation (roughly comparable to US Private Certificate with the Sports Pilot medical, I think – with some key differences e.g. you can fail the CAA Class 2 and then do the PMD and they cannot stop you) to LAPL privileges eliminates all instrument flight / IFR ops regardless of actual flight conditions. There is the remaining debate whether flying an IAP in VMC qualifies or not
For the vast majority of the UK PPL community, which never flies outside the UK (or can dig up a Class 2 holder to be PIC on a flight abroad) this is a hugely positive move. Estimates of the PMD adoption have ranged from 4k to 10k, and when seen against the usual estimate of 20k active PPLs in the UK, and with a large chunk of old-timer pilots packing it in due to loss of the Class 2 medical, this will keep a lot more people in the air.
It will also save them a bit of money and hassle. All the time you can drive, and don’t suffer from any mental conditions, you can fly. CAA page
