S/Ldr McGlashan was born in Bearsden, Durnbartonshire on 28th August, 1920. He was educated at Glasgow Academy and left there to take a short service commission in the RAF.
He began his ab initio course at 11 E&RFTS, Perth on 13th March, 1939.
Kenneth moved to 9 FTS, Hullavington on 2 June and with training completed, he joined the newly formed 245 Squadron at Leconfield on 7th November.
The squadron flew south from Drem to Hawkinge on 28th May, 1940, to cover the Dunkirk evacuation.
On the 31st, Kenneth was shot down by a Bf 109 near Dunkirk. He was slightly wounded and temporarily partially blinded by oil and glycol splashing into his eyes. He put his Hurricane into a dive and by the time his sight came back he was very low. He pulled out of the dive, blacked out and came to travelling very fast and low along a beach. Kenneth made a successful forced-landing and was rescued by British soldiers from some French colonial troops, who thought he was German. He walked along the beach into Dunkirk and managed to board a Thames paddle steamer. After an eventful crossing, Kenneth landed late at night at Margate and was taken by squadron transport back to Hawkinge.
He served with 245 throughout the Battle of Britain.

On 17th December, 1940, he was posted to 96 Squadron, then forming at Cranage for night-fighting operations. He was with it until 17th November, 1941, when he went to 60 OTU, East Fortune, as an instructor.

On 20th July, 1942, McGlashan joined 87 Squadron at Charmy Down, as a supernumerary. He took part in ground-strafing operations during the Dieppe raid on August 19. McGlashan was posted to 536 Squadron at Predannack on 12th September, 1942, a Turbinlite Havoc unit. The squadron was disbanded on 25th January, 1943, and McGlashan then joined 264 Squadron at Warmwell. He served with 264 until 15th June, 1944. He was then posted to Cairo, seconded to 2 Division BOAC, to work on the opening up of Middle East air routes.
McGlashan returned to the UK in January 1946 and joined No 1 Ferry Unit at Pershore. He moved to 54 OTU in June, remaining there until October 1948, when he was given command of 25 Squadron at West Malling. Awarded the AFC, McGlashan also received a Green Endorsement in his logbook on 21st August, 1950. At great risk to himself, he took off in bad weather to lead another Mosquito into Manston, leading it down through cloud and enabling it to land safely.

McGlashan retired from the RAF on 29th August, 1958, as a Squadron Leader.
He emigrated with his family to Australia in 1964.