Favourite mystery cover #17

Head on the Sill - Margot Neville
First published 1966 by Geoffrey Bles (UK).

Margot Neville was the dual pen name of Australian sisters Margot Goyder (1907 - 1975) and Anne Neville Goyder Joske (1887 - 1966). They wrote successful plays, novels and screenplays, including a collaboration with Joan Lindsay (author of Picnic at Hanging Rock).