Does anyone know where I or the customer might be able to obtain some Atkinson Borderer cab mounts please?
Seeing as no one has replied I’ll state the obvious ,have you tried the Atkinson club ? , if not I’ll pm you a phone number for another source . 
Try this lad Paul Allen he is based near Huddersfield and has his own restored Atki maybe he has some parts that you require. Also he is a member of the Atkinson club who have a site on flickr (paulkillers2)
paul70allen@btinternet.com