Thanks all,
The other chap will be wearing a mk3c. The jp is a mk3a and does not have live seats though i do want the helmet to do its job if i have to leave in a hurry by other methods
mart aviation has stopped selling helmets and seems to be getting rid of the related items.
HSL seem very helpful and i think what i may end up doing is buying a shell and having it fitted with alpha electronics.
Hay ho ebay here i come.
Thanks again
Mark