Scottish Airways
Highland Airways and Northern and Scottish Airways merged in 1938 to form Scottish Airways. From 1941 they carried airmail for the Air Ministry for troops stationed on the Isle of Lewis. In 1945 the airline was authorised to operate an airway letter service one way between Stornoway and Glasgow until they were taken over by British European Airways in 1947. A 4d cachet was used for receipt of the airway letter fee.
31st July 1939. First Air mail to the Orkney Outer Isles at Ordinary Letter Rate.
Perf.: 11, imperforate on outer margins.
No Value
Pale blue deep green and orange.

2nd July 1945. Air letter Service.
No Value
Air Letter Service cachet.

The Story of the Airway Letter Service 1933-1988 D. Wilson, Air Mail News June 1994
The Airway Letter Service Supplementary Notes D. Wilson, Air Mail News December 1994