[6] Seal initially entered the Patent Office in 1921, and continued to work his way through the UK Civil Service ranks within the Admiralty from 1925 onwards.

[10] Within the eight months that Churchill served as First Lord of the Admiralty, Seal proved himself to be invaluable, to the extent that just weeks into Churchill’s role of Prime minister, the 1st Earl Alexander of Hillsborough was instructed to release Seal from his daily duties, and transfer him for an extended period to Downing Street to serve as Principal Private Secretary to the Prime minister.

As Churchill’s Principal Private Secretary, [14] Seal was present at the most important strategic conferences of the early war period, and the making of key political decisions affecting the United Kingdom, such as the Attack on Mers-el-Kébir and the Battle of Britain.

Other aides during this period included Jock Colville, John Peck, Leslie Rowan, Patrick Kinna and Elizabeth Nel.

[17] Seal, in a letter to Arthur Marder, as Principal Private Secretary to the Prime Minister, described himself as “a sole survivor” from Churchill’s previous incarnation, as First Lord of the Admiralty (1939–1940).

[18] John Gerald Lang, a very able and clear headed civil servant in charge of the Admiralty War Registry, described Seal during the Norwegian campaign as “an able man” and “a very assured person and apt to be certain of the rightness of his view”.

The Churchill Archives Centre (CAC) holds a number boxes of his official work papers (from between 1939 and 1955) that cover a wide range of subject matter; from the questionable sympathies of Axel Wenner-Gren and Edward VIII, to the design of an air raid shelter at Chartwell House, Churchill’s weekend residence in Kent;[19] to when he was released for “special duties in the Admiralty” during May 1941, and was replaced by John Martin.

[33] Various sources cite an unpublished autobiography of his life, which provided a personal perspective and a first hand “working level” overview of Churchills inner circle, as well as his experiences during a critical and decisive period of World War II.

[35] A year later he became the brother in law of his colleague, Noel Atherton, through the latter's marriage to Daisy Phyllis Leadbitter, his wife's younger sister.

[43] He was a sizeable monetary contributor to the Civil Service and Post Office Life Boat Fund in aid of the Royal National Lifeboat Institution.