Continuing with the theme, here is my 'something different' not a cover, but a form used by the Armed Forces Courier Service - Form FF61, a multi-item Delivery List. The Courier Service (used for highly classified or other sensitive material) was run by the Forces Postal Service (hence the unit titles "Postal & Courier Communications") and such mail was accompanied by a RE(PS) NCO as the "courier". This service was also operated in conjunction with the Foreign & Commonwealth Office "Queen's Messenger" service so that they did not duplicate routes.
In this case the Delivery List was used for one item only - this form was used at Dusseldorf, BFPO 34 (FPO S.134) and has ARMED FORCES COURIER SERVICE / 2163 datestamp for 12 FE 70 showing this datestamp was in use at FPO S.134.
Mike :)