Deferral of the UK's implementation of the EASA requirements for validation of pilot licences for private purposes was announced in
IN 2015/028. This expires on 8 April 2016 and, unless a further deferral is announced, Part-FCL will apply thereafter. The validation rules applying to non-EASA aircraft are in the UK ANO, Article 62.
Note that the UK deferral applies
only to UK-registered aircraft.
Edited to add:
Latest from the EU Commission:
Regulation 1178/2011 Flight Crew Licensing, amendment delaying the implementation of the provisions for third country pilots licences. The Commission advised that the amendment is moving through the Council and Parliament co-decision process and should be in place by 8 April 2016. The change is intended to allow additional time to conclude a change to the EU-US bilateral aviation safety agreement to include new arrangements for Flight Crew Licensing.
So it looks as though the current deferral could be extended.