From 1st Jan 43 to 8th May1945 there are 1,658 casualties on the CWGC database with a first name initial of “K”!!
There are 63 with a “K” and surname beginning with “F”, however none of them are “Fergus” or “Fergus(s)on”. Apart from a 10 year old being certain the brevet was an “N” and that his name was Ken, is it possible that she could be mistaken about the surname, given the similarity to where he was supposedly from, Carrickfergus? Incidentally only one came up with “Carrickfergus” and that wasn’t any match to our quest.

Perhaps the best way now is to go back and ask the lady why she thinks this “Ken Ferguson” is related? What family connections take her from her family to his? It might trigger a memory that “it was Nellie and Joes boy, what was her name? She was a Smith but she married Joe Brown, not Ferguson, that was their neighbour” kind of moment….

All I can come up with so far is that the Navigator was the safest place to be if your name was Kenneth F….. !!