Grace Hamblin was born in London on 1 January 1908 and brought up near Chartwell in Kent. She attended Crockham Hill Church of England School and left at 14 for secretarial college.

At the age of 24, Hamblin was taken on at Sir Winston Churchill's home at Chartwell as a secretary. During the 1930s she worked with WSC on his history of the life of the 1st Duke of Marlborough and then became personal secretary to Clementine Churchill (CSC) in 1939. She accompanied CSC to the first Quebec (Canada) conference in 1943 and in 1945 to Russia (CSC was head of the Red Cross Aid to Russia Fund). After the end of the Second World War, Hamblin was based at Chartwell where she had responsibility for the accounts. In 1965, Hamblin was awarded the OBE and also became the first administrator of Chartwell for the National Trust, which had been handed over to the Trust after Churchill's death. She prepared the house for being opened to the public. In 1973, Hamblin retired but remained an invaluable source of information about the Churchills until her death on October 15 2002.