Buried in part Q of CAP 804:-
B. CONVERSION OF LICENCES to Part-FCL Private Pilots Licence
(1) A PPL/BPL/SPL, a CPL or ATPL licence issued in compliance with the requirements of Annex 1 to the Chicago Convention by a third country may
be converted into a Part-FCL PPL/BPL/SPL with a single-pilot class or type
rating by the competent authority of a Member State.
The pilot shall apply to the competent authority of the Member State where he/
she resides or is established.
(2) The holder of the licence shall comply with the following minimum
requirements, for the relevant aircraft category:
(a) pass a written examination in Air Law and Human Performance;
(b) pass the PPL, BPL or SPL skill test, as relevant, in accordance with Part-FCL;
(c) fulfil the requirements for the issue of the relevant class or type rating, in
accordance with Subpart H;
(d) hold at least a Class 2 medical certificate, issued in accordance with Part-
Medical;
(e) demonstrate that he/she has acquired language proficiency in accordance
with FCL.055;
(f) have completed at least 100 hours of flight time as a pilot.