[1][2][3][4] Linnell was born in Pavenham on 31 October 1878, the son of the Rev.

He was educated at Bedford Modern School, the University of London and St John’s College, Cambridge.

[2][3] During World War I he served in France, Gallipoli and Egypt, attaining the rank of Major.

[3][5] After the war, Linnell became Medical Registrar at the London Hospital.

His main interest at that point was cardiology and he worked with the esteemed cardiologists Sir James Mackenzie and Sir John Parkinson.