MAILBOAT CANCEL. 1860 small ‘ladies’ envelope to Henley-on-Thames with a wing marginal 1855-57 6d pale lilac cancelled by a barred ‘B12’Mail Boat canceller. A Henley-on-Thames 1860 arrival cancel is on the back. This B12 cancel was issued to Mr Fisher on board the "Delta" and was used on the Mediterranean Packet. Fine and uncommon. B. P. A. certificate.