Ivor Thomas was born in Hampstead in 1920, the son of Albert William Thomas and Sarah Dora Thomas (née Harries) of Buckland Crescent, Hampstead, London.

He joined the Royal Navy as a Volunteer Reserve Officer and was appointed Temporary Sub Lieutenant, RNVR on 6 November 1941. In October 1942 he was listed as serving in HMS DOLPHIN. He volunteered for ‘Special Service’ and joined HMS VARBEL at Port Bannatyne on the Isle of Bute where he trained as an X-Craft crewman. During a training exercise in Inchmarnock Water on 11 December 1942 he was serving as the First Lieutenant of HMS X4 when he was washed off the deck of the submarine in a squall, was lost overboard and was presumed to have been drowned.

The escape compartment (the Wet & Dry chamber) was flooded and the Commanding Officer (Lieutenant Basil C G Place) and the Engineer (Engine Room Artificer William Whitley) were trapped in the Submarine. The Commanding Officer managed to send a signal requesting help. Help arrived in the shape of HM Drifter PRESENT HELP.  The submarine was taken in tow and the two trapped men were released after a few worrying hours. X4 was repaired and refitted and returned to service.

Ivor Thomas was the husband of Josephine Thomas (née Parker). He is commemorated on the Portsmouth Naval Memorial on Panel No 71, Column No. 2 and on the 12th Submarine Flotilla Memorials at Rothesay on the Isle of Bute and at Kylesku.