To Tame a Sister(1961)
(The fifth book in the Mr Copplestone & The Smiths series)
A novel by Gillian Avery
Twelve-year-old Margaret hardly knows whether to look forward to a chance to mingle with the famous at her cousins' country home, or dread the mess her brothers' mischief will make of the situation.
Used availability for Gillian Avery's To Tame a Sister
September 1973 : USA Hardback
1971 : UK Hardback