Mumsy, Nanny, Sonny & Girly 1970 Loosely based on a play called The Happy Family by Maisie Mosco, screenplay by Brian Comport, direction by Freddie Francis. It was retitled to Girly when it was released in the US. It's Maisie's only writing credit. Brian has 5 other films to his credit, they appeared between between 1968 and 1972. Brian's first two films were documentaries, MNS&G was his first feature film, I haven't seen any of his other features.
Freddie was both a cinematographer and a director in both TV and feature films. I'd recently seen The Scamp, or Strange Affection in the UK, and he was the director of photography. He was the DOP for David Lynch on The Elephant Man, Dune, and The Straight Story. He directed several films for Hammer and almost as many for Amicus. He directed episodes of The Man In The Suitcase, The Champions and The Saint. I've seen a good bit of his work.
Freddie wanted to film a film in Oakley Court, it was a location that was used in several Hammer films and plenty of other films including The Rocky Horror Picture Show. You can read about it on the Wikipedia page. He'd shot three Hammer films there but all exteriors, he wanted to use the interior for his own film.
That's Vanessa Howard as Girly, Ursula Howells as Mumsy, Pat Heywood as Nanny and Howard Trevor as Sonny. They all live in the house and play The Game. It's got it's own rules and they must be followed, breaking them gets you a one way ticket to visit the Angels. Girly and Sonny leave the house to lure young men into the place, to be their New Friend, usually the New Friend doesn't last so long.
It's a house with a pecking order, Mumsy is in charge, Nanny below, the two children are on the next rung down with New Friend below them. The latest NF is slowly figuring out The Game and he starts playing the characters off of each other. It's a dangerous ploy, they could turn on him at anytime and it's off to see the Angels for New Friend.
It's pretty goofy. I enjoyed it. You might, you can see in the link above.