Vice Admiral Sir Ian Stewart McIntosh KBE, CB, DSO, DSC (11 October 1919 – 31 July 2003) was a Royal Navy officer who became Deputy Chief of the Defence Staff (Operational Requirements).

[3] In March 1941 he joined the passenger ship Britannia at Liverpool, bound for a posting with the First Submarine Flotilla based in Alexandria, Egypt.

On the morning of 25 March Britannia was sunk by gunfire from the German raider Thor approximately 700 miles west of Freetown, Sierra Leone.

7 with 82 survivors on board - 26 more than the boat was rated for - and successfully navigated 1,500 miles in 23 days to neutral Brazil.

As commanding officer of the submarine HMS Sceptre he sank almost 15,000 tons of enemy shipping and took part in Operation Source, the attacks on heavy German warships in Norwegian waters by towed midget submarines.