He was the only son of Captain James Denis Lyons and his wife Mary Josephine Dalglish.  They lived at Croom House, County Limerick which had been in the Lyons family for several generations. 

Captain Lyons owned the first car to be registered in County Limerick. It was registered on 23 December 1903 and given the registration number IU 1. It was a 10 h.p. Dequingard, and was of a dark green colour, lined with paler green. The registration fee was £1.

Montagu was educated at Ampleforth and Matriculated in 1928. He graduated with a 3rd in Chemistry in 1932 and was a public school entrant to ICI.

His mother had died in 1930.

In 1932, a Paper on “Intermetallic compounds formed in mercury“ was published in The Journal of the Chemical Society.
Alexander Smith Russell and Henry Anthony Montagu Lyons
J. Chem. Soc., 1932, 857-866
Alexander Smith Russell [1888-1972] was a Student of Christ Church and Rutherford Medallist in 1950.

In 1936, Montagu married Audrey Margaret Stark in Birmingham. They lived at Erdington and, later, at Coolbarn, Tamworth Road, Sutton Coldfield.

He was a Sergeant in the RAFVR with 100 Squadron when he was lost on 24 February 1944.
On that night, a massive attacking force of 734 aircraft made up from 460 Lancasters, 169 Halifaxes and 11 Mosquitoes attacked the German main production area of ball bearings at Schweinfurt. The plan was to split the force into two halves separated with a two-hour interval. Twenty-two aircraft were lost on the first raid and half that number on the second. The majority of losses on the second wave were caused by flak. Three hundred and sixty-two people on the ground were killed in this raid. A total of 33 R.A.F. aircraft were lost with 3 from 100 Squadron, alone.

He is commemorated on the Runnymede Memorial Panel 233.