Hi Nick,
I've looked at each of the five HMCG categories that you have on William's profile. He appears in each of them as expected. I'm not immediately seeing him appear where he shouldn't. Therefore, as Katie said, where are you seeing him in a mid-level category?
Is this : HMCG Hartlepool (1, 1, 0) as it should be? Should it not be "0"?
Look at the upper level page https://www.wikitree.com/wiki/Category:HM_Coastguard_Stations and go down the list.