Thank you Mary, I have now done what I should have done in the first place and gone to Woods Atlas. Croit-y-Killey is the property marked 73 on the Maughold map, I can be sure of this because the copy I have was g-grandfathers office copy and he has put a small pencil mark against this property also it bears his name. However it does not appear to bear any relation to Ballakilley apart from being directly opposite the entrance to the "farm street" . I suppose this must remain a minor mystery for some time to come. Thank you again.
Rick