Glasgow & South Western Railway 1904 2d dull green

Glasgow & South Western Railway, 1904 2d dull green used on a 1905 cover to Co. Leitrim, the railway stamp and postage stamp both tied by oval railway cancels in purple, both stamps cancelled again when the cover entered the mails in Belfast, with arrival backstamp ENNISKILLEN / OC 6 / 05. The back flap has en embossed emblem GLASGOW & SOUTH WESTERN RAILWAYS / HOTELS, a bit roughly opened. All evidence points to this cover being commercial.  DeLacy Spencer #8.
This is a superb example of a double transfer cover, being first transferred at Stranraer/Portpatrick to the Larne Packet, then transferrred to the Belfast & Northern Counties Railway.