In The Mystery of the Torn Parachute, Lynsdale was a bank cashier who absconded with fifteen thousand pounds in used one pound notes.
During the Second World War, Lynsdale had served as a bomber pilot at RAF Dalcross. It is then that presumably he got to know the Morayshire fairly well. After the war, Lynsdale had become a bank cashier. Over a weekend, Lynsdale took fifteen thousand pounds in used one pound notes and fled to Paris. There he changed some money into Francs at a money changer and then travelled to Marseilles where he booked a passage to the Far East on board a Portuguese tramp steamer.
While investigating the mysterious appearance of a piece of French parachute silk up a tree in Morayshire, Biggles called Marcel Brissac for assistance. Marcel told Biggles that a French Loire 4-seater aircraft was missing. It had been chartered by an Englishman, Norman Harrington White who paid for it in cash. White had asked for a parachute. The aircraft departed Le Bourget but never arrived at its destination of Liverpool. Checks with the Currency Control Board revealed that no such person had been given a currency allowance so White, or whoever he was, could not possibly have had the currency to pay for the charter.
Biggles next travelled to Morayshire and extended his investigations. There, a Captain Mackenzie of the Spey fishery board was able to provide details of all vehicular movements in the area where the parachute silk was found. Biggles' attention was drawn to one Mrs Williams. Discreet surveillance revealed that Mrs Williams lived with a bearded man who had a limp. Checks in London with Gaskin revealed that Mrs Williams was in fact Lynsdale's sister and that Lynsdale had a limp, the result of a flying accident.
Lynsdale had planned his crime well in advance, sending his sister to Scotland first, and then laying an obvious trail to Marseilles. He then chartered a plane, killed the pilot in flight, took the aircraft to Morayshire and jumped. In Biggles' opinion, however, he had miscalculated in believing that Morayshire was the ideal place to disappear to. In reality, it was the worst possible choice of refuge. In view of the sparse population, the local residents were alert and took notice of all strangers. The roads were also heavily patrolled in order to control salmon poaching. We can assume that Gaskin eventually arrested Lynsdale and he was tried for theft and murder.