Railway Air Service. 
On 12 April 1933, the Great Western Railway of Great Britain started an air service between Cardiff, Torquay and Plymouth, and later Birmingham carrying railway letters by airplane. A special stamp was issued on 15 May 1933 for this service, a 3d airmail which was not only Britain’s first airmail stamp, but also one of the world’s largest. (Figure 1). This service operated until the onset of winter.
The service was expanded in 1934 to include Belfast, among other locations. (Figure 2). The service was now backed by the “Big Four” railways (Great Western Rwy, Southern Rwy, London Midland & Scotland Rwy, and London Northeast Rwy), thus GWR stamps were no longer used. This service was covered under the 1890 Agreement between the Postmaster General and the Railways for the movement of express mail under railway control rather than Post Office as long as an appropriate postage stamp was applied and canceled. The Post Office handled final delivery to the addressee. The operation was halted in the fall of 1934 due to weather and was not resumed.