I've heard - but not seen, that there was an almost identical story - the Shepherd is also a ghostly Mosquito - published in "The Aeroplane" in 1954, It is called "A Christmas Story" by an R. Leach. Can anyone confirm/deny?
I found it this afternoon - published on 24 December 1954, pages 932 and 933. The story concerns an airliner flown (i.e. captained) by a former Mosquito pilot. Over the North Sea the radio fails after the radio officer reports "the whole of the South is clamped". After the Mosquito leads them to a safe landing the mess servant tells our pilot about a man for whom he was batman, who used to "hang around if there was anyone in trouble and help guide them back... Poor chap. Disappeared just ten years tonight. Never seen again."
The WIkipedia page for the book
https://en.wikipedia.org/wiki/The_Shepherd says "Many have speculated references to preexisting RAF folklore. While Forsyth is a former RAF pilot and could have heard and adapted such a story (either with or without the intent to do so) no references or anecdotal evidence have been put forward to support such claims."