MP Sir Roger Gale offered Margaret Thatcher advice ahead of TV cameras being introduced to the House of Commons, once-secret documents have revealed.

The 73-year-old Conservative drew on his experiences gained as a director and producer working on radio and television, telling the late Prime Minister where to direct her gaze and how to stand at the despatch box.

Details of the Herne Bay MP’s advice was only made public this week as a confidential note he wrote to Mrs Thatcher in 1989 was released by the National Archives.

In it, he wrote: “Ministers should seek to reinforce the authority of the Chair by addressing all remarks to and through the Speaker, favouring either Camera 1 (profile) or Camera 2 (straight to camera).

“Leaning on the customary left arm of the despatch box will present the appearance of a back to the Speaker and weaken the authority of the Minister. Ministers will need to learn to lean on the right arm when reading notes!”

Sir Roger also suggested that Mrs Thatcher look over the head of the Opposition front bench in order for it to appear on camera that she was looking directly at Labour leader Neil Kinnock.

His note said: “The camera angle on the front benches is fairly acute. To gain the impression of looking the opponent – Leader of the Opposition or Spokesman – in the eye, it may be necessary to ‘cheat’ the eyeline over the head to Camera 2.”

Sir Roger said this week that he was surprised the note had surfaced after almost three decades.

“This was a private letter and I didn’t even know they kept this stuff, but I can’t deny it because it’s true,” he said.

“Mrs Thatcher trusted people who knew what they were talking about. I was a producer and television director and at the time probably had as much expertise as anyone and offered the advice.”

Sir Roger had worked for radio stations including Radio Caroline and the BBC’s Radio London.

He was later the director of BBC children’s television before joining Thames Television in 1979, where he worked until he was elected to Parliament in 1983.

Despite his background, Sir Roger – who was knighted in 2012 – opposed the introduction of cameras to Parliament.

He said: “I knew then what would happen. It did happen. It lead to grandstanding.

"The real purpose wasn’t to enhance democracy, but to provide the television stations with clips for their news programmes. It rewards outrageousness.

"If the person who talks before me is outrageous, then I have to be more outrageous to get my clip aired.

“The population has gone from being ill-informed to being misinformed. They watch a few minutes of the chamber and think this is how things are.

“Well, it’s not. Most of the work is done behind the scenes in committees.”

Sir Roger’s note to Mrs Thatcher was released on New Year’s Day. It also emerged that Anthony Jay, who wrote the political satire Yes Minister, had given ministers advice about speaking at the despatch box.