Number 10 officials worried that Margaret Thatcher would crash a new Rover model when asked to do a three-point turn in Downing Street during a planned test drive, her newly released private office papers show.

The new Rover 800 was quietly delivered to Chequers instead, towed by a white Range Rover the week before, so that the Conservative prime minister, who had probably not driven regularly for more than 10 years at that point, could “get the hang of the car” before the test drive in front of cameras.

Thatcher’s private papers released on Monday by the Margaret Thatcher Foundation show that the test drive on 10 July 1986 had been arranged as part of the launch of the first executive Rover model after the company changed its name from BL to the Rover Group.

Thatcher agreed to it after her private secretary, Nigel Wicks, recommended it, saying: “Worthwhile, if she would do it, to demonstrate ‘we still love Leyland’.” The British company, which was by then jointly owned by Honda, was losing more than £100m a year.

The private practice drive went ahead at the prime minister’s country retreat, with Thatcher told that it was “only an opportunity to familiarise yourself with the car. There will be no publicity.”

Downing Street officials then drew up options for the PM. “The most straightforward way of arranging this would probably be for you to drive the car from the front door towards the bottom of Downing Street, reversing into the side road, and then driving back up the street to the front door,” advised Mark Addison, of her private office.

“If you would like to handle the test drive in this way, you would need to feel fully confident about manoeuvring the car into the side road and back out again. The alternative would be to walk down to the car at the bottom of Downing Street and drive it back to the front door. Agree to the first option? Or prefer to keep it simple?” asked Addison. “First option,” replied Thatcher, who once said: “The lady’s not for turning.”

The video footage of the test drive shows that she had no trouble on the day reversing the car in Downing Street.

Her press secretary, Bernard Ingham, had also ensured that Austin Rover did not repeat the mistake it made when she had previously test driven an Austin Maestro in Downing Street and delivered a red car by mistake. “They are fully aware of the importance of getting the right colour this time,” reported her private office.

Thatcher later made clear that she had been impressed by the car’s design, smooth handling and comfort but not its price. She told friends that, much as she liked the blue Rover, at £19,000 for the top of the range model it was too expensive for her and her husband, Denis.