From CAP 804, see below- same as now, 100 hrs, 25 solos
FCL.910.FI FI – Restricted privileges
(a) An FI shall have his/her privileges limited to conducting flight instruction under the supervision of an FI for the same category of aircraft nominated by the ATO for this purpose, in the following cases:
(1) for the issue of the PPL, SPL, BPL and LAPL;
(2) in all integrated courses at PPL level, in case of aeroplanes and helicopters;
(3) for class and type ratings for single-pilot, single-engine aircraft, class and group extensions in the case of balloons and class extensions in the case of sailplanes;
(b) While conducting training under supervision, in accordance with (a), the FI shall not have the privilege to authorise student pilots to conduct first solo flights and first solo cross-country flights.
(c) The limitations in (a) and (b) shall be removed from the FI certificate when the FI has completed at least:
(2) for the FI(H) 100 hours flight instruction in helicopters and, in addition has supervised at least 25 student solo flight air exercises;