S30 – Cayman Islands First Day Cover 1937 on Selfridges Philatelic envelope R and B cancels

Cayman Islands. First Day Cover, 12th May 1937 – date however is not visible, so called it a used set. Envelope has Selfridges Philatelic embossed on reverse flap and R and B cancels on front. In good condition and unopened. Please see photographs.