The Royal Collection Trust is seeking voluntary redundancies amid the “greatest challenge” in its history.

The charity is facing predicted losses of £30 million over the next year, and has taken out a £22 million loan to enable it to continue following the closure of royal palaces and galleries to the public during lockdown.

Its income comes from visitor admissions to tourist attractions such as Windsor Castle, the Palace of Holyroodhouse, the summer opening of Buckingham Palace, and the Queen’s Galleries in London and Edinburgh, and related retail sales.

The trust maintains and displays the large collection of royal artefacts from artwork to furniture held in trust by the Queen for her heirs and the nation, and carries out other charitable work.

Voluntary redundancy is open to all staff, currently around 650 people.

Once the scheme has closed, the trust will decide whether future restructuring is needed.

A spokeswoman said: “The Covid-19 pandemic has posed by far the greatest challenge to Royal Collection Trust in the charity’s history.

“The closure to the public of Windsor Castle, the Palace of Holyroodhouse, the Royal Mews at Buckingham Palace, and the Queen’s Galleries in London and Edinburgh has had a very significant and serious impact on our finances, as we are entirely funded by visitor income from admissions and related retail sales.”

It hopes to reopen the palaces and galleries including Windsor to the public in late July on a five-day week with closures on Tuesday and Wednesday.

But the summer opening of Buckingham Palace remains cancelled as the required social distancing means the trust would have made a loss.

The spokeswoman added: “While we have taken out a £22 million loan to enable us to continue to operate in the near future, we need to do so with a lower cost base to recover our financial position.

“Inevitably this must include a reduction in staff costs, which is our greatest single expense.”

The trust, which usually brings in £77 million a year, has already reduced its exhibition and learning programmes, cancelled or postponed major projects and frozen recruitment in a bid to save money.