I have to do two IRs each year also, one MPA and one SPA, which has helped me to understand the problems!
To answer your question, if its the latter case then (never held SPA IR) your applicant will need to do training as required then an initial SPA IR Skill Test with an IRE if they want a IR-SPA.
If its the former (current MPA IR and expired SPA IR) your applicant will need to do training as required (maybe nothing) then a IR Proficiency Check with a CRE/IRR. NEXT TIME they come to revalidate they can use cross-crediting.
If he wants an IMC Rating (annotated IRR on EASA licences) then he can contact the CAA for a reduced course requirement (probably as required) and then complete the IMC test with a FE.
ifitaint...