In The Case of the Murdered Apprentice, Mr Green was the postmaster at the village post office in Buckbury who assisted Biggles in his investigation into the murder of aircraft apprentice Edmund Teale. Green supplied Biggles with background information about Larford Hall, noting that Mrs Karena Vanester frequently sent letters to Holland and usually to the same address: that of Rudolf Lurgens at Rosenhalle, near Hillegom, Holland.
Believing that Lurgens was the murderer, Biggles wanted to lure him to Britain. With Green's help, Biggles sent a telegram to Lurgens asking him to return to Britain that night because of important new business, signing off the telegram as "Karena", the same way Mrs Vanester signed off her messages.
Green also complied with Biggles' instruction to block all calls to and from Larford Hall. Green assured Biggles he could be relied upon to do his part. He had known the murdered Edmund Teale since he was a toddler.