Alexander Kerr was born in Glasgow on 19 December 1881, the son of Thomas Kerr and his wife Margaret (nee Bradshaw). Clearly a proud Scotsman, his many tattoos included a thistle on his chest.

He entered the service as an acting ERA 4th Class on 18 March 1904. Before submarines his drafts included the armoured cruiser HMS SUTLEJ on the China Station where he was confirmed as a 4th Class ERA, standing by the cruiser HMS SAPPHIRE while under construction at Jarrow where he became an ERA 3rd Class in March 1907.

In 1911 he was rated ERA 2nd Class and that year he married Nellie Swann from Buckland, Portsmouth. He was rated 1st Class ERA on 15 March 1916 and Acting Chief ERA on 1 July 1916.

He and his wife lived at Portsmouth and he is remembered on the Portsmouth Naval Memorial.