Balmoral, where they are on holiday. The children cook – Prince Charles even makes a salad dressing – and then the Queen takes a young Prince Edward to a sweet shop, dismissing the widely-held belief the monarch doesn’t carry cash.

In another “behind the scenes” moment, Prince Charles can be seen practicing the cello when the string of the instrument snaps in his brother’s face.

In more public-facing events, the film also touched on the family playing host to the Great Britain Olympic team, having lunch with Richard Nixon, and Princess Anne visiting a North sea oil rig.

When was it broadcast?

One month before the film went to air the Queen watched it in its entirety and the contents were finalised by an advisory committee chaired by Prince Phillip.

It went to air on BBC One on 21 June 1969, where it was watched by 30.9 million viewers in the UK, and then again a week later on ITV where it was watched by a further 15 million people.

What was the criticism?

The intention had been to give the general public a look behind the curtain. But critics said this was not the purpose of monarchy and as such, the film had been a flop.

Media reception was generally negative with David Attenborough, who was controller of BBC Two at the time, going so far as to claim the film was in danger of “killing the monarchy”.

In 2018 historical consultant Robert Lacey, told ABC News that the family realised if they did things like this too often they would “cheapen themselves, letting the magic seep out”.

As a result the Queen decided not to deliver a Christmas message in 1969 because she was worried about “overexposure” of the royal family.

Although the Royal Family wasn’t pulled from broadcast immediately, it was shown again for the last time on BBC in February 1972, and then never again.

In an interview, press secretary Heseltine, who had reportedly been instrumental in selling the idea to the royal family, explained the reason they put “very heavy restrictions” on the film was because they realised they had encountered a “huge shift in attitude”.

Can we view the film today?

In the 1990s the film could be privately viewed by historical researchers as long as they got permission from Buckingham Palace beforehand and paid a one-off fee of £35.

Broadcasters have been allowed to use short clips in other documentaries for example as part of the BBC’s “The Duke at 90”, shown in 2011.

Today Queen Elizabeth retains the copyright to the Royal Family, something which Richard Tomlinson wrote in The Independent in 1994 was “a sign” she regarded the film as a “mistake”.

He continued: “At the time, it was hailed as the latest example of the British dynasty’s miraculous ability to reinvent itself, just at the moment when disaster beckoned.”