[1] Nasmith was born on 1 April 1883 at 136 Castelnau in Barnes, which was then in the county of Surrey and is now in the London Borough of Richmond upon Thames.

He embarked on HM Submarine D4, under then Lieutenant Nasmith's command, and (in the words of The Times of 10 May) "made a lengthy run in her when she was submerged."

What made the occasion all the more remarkable was the presence on board of his second son, Prince Albert, who was to become King George VI, of Winston Churchill (First Lord of the Admiralty and future prime minister), and of then Captain Roger Keyes, Inspecting Captain of Submarines, who was to become the first Director of Combined Operations (the Commandos) in the early part of the Second World War.

Nasmith's diary records that: "We remained under water for ten to 15 minutes, during which time he showed great interest in the proceedings, periscope in particular."

A Navy News article from July 2012 by Commander William Corbett (at whose parents' wedding Nasmith had proposed the toast to the health of the bride and groom), records that Nasmith often wondered what would have happened to the course of 20th century history had he sunk that day, a not unreasonable thought, given that he had very nearly sunk in the Solent in 1905 whilst in command of HM Submarine A4.

When he had safely passed the most difficult part of his homeward journey he received information that a cargo of coal was heading towards Istanbul from the Black Sea.

When the coal-carrying ship came into sight of the docks, a welcoming committee of municipal grandees soon formed, along with a happy crowd – water, electricity and rail transport had all suffered due to a lack of coal.

[10] Later in the war, Nasmith was in charge of the Seventh Submarine Flotilla in the Baltic and Senior Naval Officer at Reval (later Tallinn), and was appointed CB in 1920 for that service.