Joan Bright Astley had a remarkable career working behind the scenes in Whitehall corridors of power during the Second World War.

Penelope Joan McKerrow Bright was born in Argentina — where her parents had met — in 1910. She was the middle daughter of five sisters of an English accountant and a Lowland Scottish governess. The family had good manners, but not much money; there was no question of expensive schooling or of going to university. After returning to England, the family moved around between Derbyshire, Bedford, Bath and finally Bristol.

Bright was educated at a mix of local schools and by a governess. She learned typing and shorthand, and by good luck succeeded an elder sister, Betty, as a clerk in the British legation in Mexico City.

After some exhilarating years there, in which she came to know George Gershwin, the American composer and pianist, she returned to England in 1936. She was offered two jobs, one with Duff Cooper, who was working on his biography of Talleyrand, and one in Germany as an English teacher to the Hess family. She turned down both and took a job as a typist with the Territorial Army.

In April 1939, after brief spells at Chatham House and elsewhere, she took up a post in a semi-secret branch of the War Office. She worked under J. C. F. Holland, a Royal Engineer of great originality who headed MI R — the R stood for research — and researched into methods of irregular warfare. Holland started the Commandos, then comprising stay-behind parties who were to have disrupted the petrol supplies and communications of a German invasion of England. He also led the deception service and the Special Operations Executive — into which what was left of MI R was absorbed.

Bright was briefly a colleague of David Niven in MI R. Niven used to keep two hats, one in his room and the other with a folder of typescript in the porter’s entrance lobby. He told her that this meant no one knew whether he was in or out. Bright typed all the secret documents, kept the war diary, and most importantly, did not gossip.

She next joined the secretarial staff of the Joint Planning Committee, and was picked to run the Secret Intelligence Centre. This was a single room, in the sub-basement of the Cabinet War Rooms at the southeast corner of St James’s Park.

In the SIC she kept copies of all the Chiefs of Staff and the Joint Planning and Intelligence Committees’ minutes, and any particularly secret papers that arose out of them. Commanders-in-chief from abroad, visiting London for briefings, were sent down to see her and go through her collection: this was reckoned much more secure than sending the documents overseas. But although she lived close to the centre of affairs, she was not cleared for ultra-secret intelligence, of which she first became privy to in 1973.

Initially, she was apprehensive in her new role and her room looked like a doctor’s waiting room. She need not have worried, she was an attractive young woman with a matching personality, so it was not long before the Commanders-in-Chief were making regular visits. They enjoyed being greeted by someone who did not spring to attention, and were then able to relax, read and perhaps express strong views that might be agreed with but instantly forgotten.

She became familiar with some of the commanders, including General Wavell. It was not unusual for Wavell to drop into Bright’s information room on return from the North African desert in order to “put himself in the picture”. When he became Viceroy of India in 1943 he wanted Bright to come with him to set up a secretariat.

Bright continued not to gossip, and was promoted to be personal assistant to General Sir Hastings “Pug” Ismay, who was Chief of Staff to Churchill as the Minister of Defence. Between the Quebec conference of 1943 and the Potsdam conference of 1945, Bright organised the administrative arrangements for British delegations at six conferences abroad.

One day in the spring of 1943, General Ismay put his head round her door and said: “Would you like to go to Washington?” Her role was to be an administrative officer for the British delegation to the meeting of President Roosevelt and Winston Churchill to determine war strategy. It proved a daunting task but she rose to it with competence and humour, even placating an ashen-faced civil servant told to share a cabin on the Queen Mary with an arch rival, only to discover that the sharing included the bed.