During the war, Glibb had served in the R.A.F. together with his twin brother, Flying Officer Charles Glibb. Both were bomber pilots who served two tours of combat missions.
After the war, both brothers had continued in service. However combat flying had taken their toll on John's nerves and twice he was nearly discharged as being mentally unfit but he requested to stay on. When Charles was arrested for embezzling mess funds, John became unbalanced and stole a Halifax with a war load, threatening to drop the bombs in two days on the Royal Aircraft Establishment at Farnborough unless Charles was released.
When nationwide searches failed to find the Halifax, Biggles turned to studying John's service docket for a lead. He found a flimsy clue that John had a wildfowling hobby and sent Algy to ask John's mother, Mrs Glibb where John would typically do his hunting. Mrs Glibb revealed that John used to be posted to Aucherlocherbie and would send her ducks from there. Biggles remembered that this was a remote bomb experimental depot in Sutherlandshire in North Scotland which had since been abandoned.
Hurrying north in the Proctor, Biggles and Ginger parachute into Aucherlocherbie and find John in a hangar sitting next to his Halifax crying. John tells them it had all been his fault. Charles had taken the mess funds at his behest because he had wanted to help a friend who was in debt. He had wanted to repay Charles with his next month's pay but the surprise audit had come too soon. He did not really intend to drop the bombs and he could prove it because he had dropped them all into the sea. Biggles convinced John to come with him and face the consequences. John agreed, saying that if he could face the flak up the Rhine for two years, he could take "a little thing like this".
John was court-martialed together with his brother Charles, but in view of their war records, and the fact that the money was repaid, the court took a lenient view and sentenced them to nothing more than a severe reprimand.