This 1999 Millennium Countdown Workers 1 crown coin cover is a Benham first day cover. It's named Great Feats of Engineering and hosts a brilliant uncirculated Isle of Man one crown coin and Royal Mail commemorative stamps dedicated to aspects of engineering. Cancelled postmark Workers Shipbuilding & Tunnels Greenwich London SE10 4th May 1999.
The Benham cover is pre-owned, comes complete with a certificate of authenticity and enjoys a limited edition of 1000.