The Cuckoo Tree - Joan Aiken - Bog

While her friend Capt Hughes recovers from a carriage accident, Dido is marooned with the odd inhabitants of the Tegleaze estate. a priceless possession is stolen, a boy kidnapped, a twin sister found and when Dido catches a glimpse of her rascally father in Petworth, she is sure she is in the midst of another wicked Hanoverian plot.