Railways (Conveyance of Mails) Act 1838

Postmaster general may direct mails to be carried on railway in mail coaches, in lieu of company’s carriages.

4. In case the postmaster general shall at any time be desirous of sending by any such railway any of her Majesty’s mail coaches or mail carts, with the mails or post letter bags and guards thereof, and carriages for sorting letters, with any officers of the Post Office therein, instead of sending the said mails or post letter bags, guards, and officers of the Post Office by carriages to be provided by such railway company as aforesaid, then and in any such case such railway company shall, at the request of the postmaster general, signified by such notice as aforesaid, cause such mail coaches or mail carts, with the mails or post letter bags and guards thereof, and carriages for sorting letters, with any officers of the Post Office therein, to be conveyed by the usual or proper trucks or frames on their said railway, subject to such regulations and restrictions of the postmaster general as herein-before mentioned.