rogue leader, if you're after a CPL(A), you might wish to look at CAP 804 Part I Section 4 part L page 11 (it's .pdf p401/930):
(e) Hours as PIC of other categories of aircraft may count towards the 200 hours flight time, in the following cases:
(i) 30 hours in helicopter, if the applicant holds a PPL(H); or
(ii) 100 hours in helicopters, if the applicant holds a CPL(H); or