I should imagine the CAA would insist on a pass in (at least) the CPL/ATPL 'gas turbines' and 'AC electrics' exams as well?
When I originally obtained my BCPL and AFI Rating the CAA would not issue the licence until I had passed the 'gas turbines' exam. I complained bitterly that I was only instructing on and flying in SEP aeroplanes, but they wouldn't have it. So my licence was initially issued only after having passed in the optional subject of Gas Turbines!
Bizarre but true!
KR
FOK