Monica was actually a comedienne which she returned to successfully during the '60s and '70s - as per my other posts on her. Add in Dirk Bogarde being screamingly camp as arch-villain Gabriel with the blonde wig and those sunglasses, and Terry Stamp as that bit of rough Willie Garvin and all those wonderful moments, a lot of which are captured here.
I was at the premiere in Leicester Square and saw Bogarde with Rosella Falk (Mrs Fothergill!) on his arm - Monica was not there, but was at the premiere of DARLING with Dirk and Julie Christie in 1965 (above), when they were filming MODESTY. We love this Losey with the Dankworth score, and the full movie is available here: https://www.youtube.com/watch?v=9BpC0NatYqU