The Traveling Post Office (TPO) has been a fixture on Britain’s railways since mail was first carried on trains in the 1830s. 

The sorting of mail in transit gradually reduced in the 21st century as mechanised sorting at depots became commonplace and concerns about the safety of workers carrying out letter-sorting at increased main line speeds. The last TPO using carriages in the UK took place during the night of 9th January 2004. After that, a fleet of Royal Mail-branded Class 325 EMUs continued to carry parcels by rail, but these too ceased in 2024. TPOs could collect and deposit mail on the move by means of lineside apparatus. Several of these vehicles have survived in preservation.

This Hornby RailRoad model coach features a working mailbag transfer mechanism.