I have established that the cap is velvet and that it was made by Rowan & Co, 104 Argyle Street, Glasgow. I have tried to contact Scotland Rugby News but was unable to upload a picture. I sent an email to ask them for further information but as yet had no reply. I have contacted the University of Glasgow archives, who have responded very quickly (as usual) giving some further ideas including one - Sports Heritage Scotland to whom I have just sent the details. I have also contacted Glasgow City Archives but as yet I have had no response. My initial email that I sent to Allan Glen rugby club remains unanswered.
I would like to thank you all for your suggestions & help. Will let you know if I am successful.