Great Western Railway
In 1933 the Great Western Railway inaugurated an air service between Cardiff, Newport and Plymouth, via Exeter, using a Westland Wessex supplied by Imperial Airways. Mr. A. Phillips suggested carrying flown covers on the first flight of this service on 12th April 1933. Although the railway company was allowed to carry letters under the railway letter agreement, it was not clear whether the agreement would extend to airmail. It was agreed that Mr. Philips would carry the covers, charged at the regular railway letter fee of 3d. for an item not exceeding 2oz, as a passenger. At Newport and Cardiff a newspaper parcel label was attached to the covers, but as Plymouth did not have any the covers were hand stamped with the parcels department cachet.

The Postmaster-General subsequently agreed to the carriage of mail by the Great Western Railway's air service and the issue of an air fee stamp, starting on 15th May 1933. A week later the service was extended to Birmingham. The last mail flight was on 30th September 1933, but due to fog only between Birmingham and Cardiff.

Covers were produced, including one by British European Airways, to commemorate the 40th anniversary in 1973. The 50th anniversary in 1983 was also commemorated by the issue of covers, a facsimile of the original G.W.R. air fee stamp overprinted "1933-1983 50th Anniversary" and a label issued by the Didcot Railway Centre.
12th April 1933.

Black on green. Prepaid Newspaper Parcel label.

No value
Plymouth parcel cachet in purple.

15th May 1933.
Designed by G Sawyer. Printed in lithography by Waterlow and Sons, Ltd., London in sheets of 20. Perf.: 10.
Green with a red serial number. Westland Wessex.

G.W.R. The 1st Commercial Air Mail Flown in Great Britain Air Mail Magazine Volume 1, pp. 4-6, A. Phillips (1939)
Great Western Railway Air Mail Magazine Volume 2, pp. 268-269, A. Phillips (1940)
The Air Mails of the British Isles Chapter 2, H. Stanley Redgrove, Privately Printed, (1940)
Great Western Railway Air Services David Potter, Railway Philately Volume 7 Number 3, June 1973, pp. 88-89
Great Western Railway Airway Services Norman Williams, David Potter. Cinderella Corner, Stamp Magazine, November 1976
Official British Inland Airmails Part 1. John C.W. Field, British Philatelic Bulletin, Volume 24 Number 6, January 1987
The Story of the Airway Letter Service 1933-1988 D. Wilson, Air Mail News June 1994