In The Bird That Died of Diamonds, Colonel Colin McGill was a retired army colonel and a friend of Air Commodore Raymond who found diamonds inside a pheasant he had shot for his dining table.
McGill kept an estate at Tomlecht in Morayshire where he took paying guests for the shooting season as a source of income. Among his prospective guests had been one Baron Zorrall who had written to him from a hotel in Monte Carlo. In due course, Zorrall's guns and cartridges arrived at Tomlecht but the Baron himself never showed up. Enquiries with the Monte Carlo hotel revealed that no Baron Zorral had ever stayed there.
Towards the end of the hunting season, McGill wanted a pheasant for his table. Finding that he had run out of cartridges, he borrowed one of the Baron's and shot a bird with it. While dining on the pheasant, McGill discovered several diamonds in the carcass but no lead shot. He surmised that the cartridge he fired must have been stuffed with gems. He next cut open a few other cartridges and discovered rubies and pearls. Astonished, McGill handed his find to his friend, Air Commodore Raymond at Scotland Yard.
Raymond was able to identify Baron Zorrall as the assumed name of an international jewel thief also named Zorrall. The jewels McGill had brought in were those of a jewel theft from the villa of one Countess Castelano on the Riviera. Zorrall had evidently smuggled the jewels into Britain hidden inside shotgun cartridges. He probably intended to link up with his luggage at Tomlecht but had been murdered enroute at the Crestata Hotel in London. Biggles believed that Zorrall's murderer might have been an accomplice of the original jewel theft. If so, he would be interested in locating the jewels and would guess that they might be hidden with Zorrall's guns or luggage at Tomlecht since they were not found at the Crestata Hotel. With the Colonel's help, Biggles laid a trap for the murderer. Advertisements were planted in shooting magazines inviting Baron Zorrall to collect his guns from Tomlecht as a bait while Biggles and the Colonel lay in wait.