Bear in mind that Bristow completely rebuilt G-AYNP,with the Series 3 nose mod for the Gnome and new cranked tail.In fact the only original Mk3 bit was the centre section. To be really anoraky it was delivered to Westland at WSM in late'69 to have the structural changes made to the front end before going to Redhill by road to have the new tail boom and everything else fitted.
Modifying just the tail boom was a fairly simple operation and several of the late production RN Mk3s were retrospectively fitted under Mod 170 with the cranked version in service.It was standard from 1056 on the Mk7.