Griffo, there is a chance (given SP's comments) that 901 may have been the very craft used to pluck your Dad from the Seahawk!
I may have asked this before and if that's the case then my apologies but .. do you have any photos from your Dad's flying days?
The permission for this came in sooner than I anticipated .. so here is
another photo of
another Dragonfly taken by
another Clarke at Chatham!
Westland Dragonfly WG664 bearing the identifier '533' visiting Chatham Dockyard in 1957 (Photo: Malcolm Clarke)
As an aside, the last two vessels to be built at Chatham (both Oberon-class submarines) were
Ocelot (for the Royal Navy) and
Okanagan for the Royal Canadian Navy.