In The Case of the Lunatic at Large, Flying Officer Charles Glibb was an R.A.F. Flying Officer who was arrested for embezzling station mess funds.
Charles joined the R.A.F. together with his twin brother Flying Officer John Glibb during the war and served two tours as a bomber pilot. He remained in service after the war and at the time of the story was the Mess Secretary of his station. A surprise inspection by an Air Ministry accountant revealed that some money which should have been in Charles' safe had gone missing. Charles admitted taking the money but did not offer any explanation and in consequence he was placed under close arrest pending a court martial.
His arrest unbalanced his brother John who stole a Handley Page Halifax bomber and threatened to bomb the Royal Aircraft Establishment at Farnborough in two days unless Charles is released. Biggles' hunt for John forms the main plot of the story.
At the end of the story, it emerged that Charles had taken the money at John's behest in order to lend it to a friend who had gotten into debt. John had been planning to replace the money with the following month's pay but the surprise inspection came before he could do it. The twin brothers were both court-martialed but the court took a lenient view, given that the money was repaid. That, and taking into account their war records, their sentences amounted to no more than a reprimand.