Jack Churchill at Chartwell

Signatures in Churchill's visitors book at Chartwell, a National Trust property in Kent

John Strange Spencer-Churchill (1880-1947), always known in the family as Jack, was Winston Churchill’s younger brother.

Major John (’Jack’) Strange Spencer-Churchill, DSO, TD (4 February 1880 - 23 February 1947), was born at Phoenix Park, Dublin, Ireland, where his father, Lord Randolph, was secretary to Jack's grandfather, the 7th Duke of Marlborough, then Viceroy of Ireland.

Jack showed academic promise from the beginning. At age twelve he joined Winston at Harrow but soon found his brother to be a noisy and disruptive companion. He was again constantly top of his class. As the sons of Lord Randolph Churchill, both boys attracted much attention at Harrow.

His father planned an Army career for him but Randolph's tragic early death was to change all that. Instead, his mother Jennie, using her close friendship with the Prince of Wales, the future King Edward VII, saw him introduced to the banker Sir Ernest Cassel. Jack was taken on as a personal assistant to Cassel.

In December 1899, in the early months of the Boer War, he went to South Africa to join his brother as a lieutenant in the South African Light Horse regiment, which Winston had joined after his escape from a prisoner-of-war camp.

Afterwards, resuming his career as a stockbroker, he went on to join the firm of Vickers da Costa. He became a valued source of financial advice for his brother and others members of the family.

The families saw a great deal of each other and thanks to Winston's successful political career, and also to Jack's artistic wife Gwendeline (known in the family as Goonie) and her wide circle of friends, Jack became closely acquainted with many of the leading politicians, writers and artists of the day, including the Asquiths, the Laverys and J.M. Barrie.

In the First World War Jack saw active service with his regiment in Flanders, serving with distinction in the First Battle of Ypres. His fluency in French then saw him appointed to British General Headquarters in France. He ended the war as Military Secretary to the Fifth Army.

Jack's wife Lady Gwendeline died in 1941. When his house was bombed in the Blitz he moved in with Winston and Clementine at 10 Downing Street.

He is buried near his parents and brother at St Martin's Church, Bladon, Oxfordshire.