MYSTERY surrounds the latest filming project to be given permission to use the Knebworth House estate.

In the past the stately home and its magnificent grounds have been the backdrop for films that have included The Kings Speech, Nanny McPhee, Batman the Movie and St Trinian's.

And in the Netfix smash The Crown, the inside of Knebworth said to have been used as a substitute for the inside of the Queen's Balmoral home.

Series five of The Crown is set to be filmed from June and on Thursday a meeting of North Herts District Council's planning control committee approved plans for a new film set in the grounds of the estate, to operate for 23 weeks.

Planning officer Sam Dicocco told the committee he had already visited the site, where work on the set had already begun.

But such was the level of secrecy, he told councillors, that he had had to sign a non-disclosure agreement before being given access.

Even then, he said, he left the site without knowing what was being filmed there.

According to the officer's report, the set (coving an area of 128m by 102m) would contain temporary structures presenting as dwellings and garages.

And they would be set in between trees on the south drive along a temporary roadway, with driveways.

There would – according to the report – also be a crew area (covering 60m by 57m) that would require the laying of aluminium panels alongside a marquee, as well as four containers and ancillary vehicles.

Councillors heard that the work would also require the temporary removal of part of an existing 'bund' on the site.

And it was reported that some 'neighbours' – while having no objection in proncipe – had raised issues relating to potential noise created by delivery and construction, the long working days proposed and the potential impact on wildlife.

At the meeting the application received unanimous approval from the committee.

Conservative Cllr David Levitt said that although the report had indicated there was no specific mention of film sets in the Local Plan, there was policy under its economic development framework to encourage film and television production.

And he said: "We do have council policy that encourages filming in the district.

"It brings in employment, it brings in tourism and it brings in fame and fortune from appearing on the television, which brings people into the district.

"I whole-heartedly support this development."

And Cllr Terry Tyler said the project would help to fund repairs at the stately home.

"I had the privilege last year of being – in my civic year – of being a trustee for Knebworth," said Cllr Tyler.

"I know that they are desperate for funds to repair the house – and obviously this venture will actually help them repair some of the expensive repairs that need to be done. So I fully support this."