On the photograph, there is a large letter 'T' to the left of the serial. Can I infer that there would be a similary large letter 'W' to the left of the serial on WL746? I ask as this may help me find a picture of WL746 amongst several I have where the serials are unreadable
I really cannot help with this, but assume others may know what identification letters were painted on which aircraft. However WL746 the one you're after was Ballykelly based whereas WL743 the one in my photo from 42 Sqn at St Eval in Cornwell and it may be that individual squadrons/bases had their own method of numbering aircraft with the possibilty that this type of "individualism" went on, but I suspect otherwise and that the paint schemes and numbering were common throughout Coastal Command as directed by HQ.