I remember flying with the Manston unit in 1971.The two Whirlwinds were turbine conversions of a couple of old Navy Mk.3s but as I took only b/w pictures I had forgotten the colour scheme.
I see G-BIMU is still around too,just retired from SAR ops in the Netherlands.This S-61N was with BCAL on the Gatwick link when it first arrived in the UK but is best known for its Bristow SAR work.
Sadly efforts so far to save any S-61N for The Helicopter Museum have failed but I wonder if the new Bristow CEO will be more sympathetic to the cause? 'MU deserves to be preserved.