The Queen has continued with her official duties by holding calls with the Chancellor and the head of the British Army, as the Duke of Edinburgh undergoes testing in hospital for a pre-existing heart condition.

On Tuesday evening, the monarch carried out her traditional pre-Budget audience with Rishi Sunak, ahead of his statement on Wednesday.

Mr Sunak was pictured on the Treasury’s Twitter account at his desk as he spoke to the head of state on the telephone.

Earlier, in her role as Head of the Armed Forces, the monarch, 94, spoke with Chief of the General Staff, General Sir Mark Carleton-Smith, by phone from Windsor Castle.

The pair discussed how the Army has continued to support communities throughout the UK amid the coronavirus pandemic, as well as carrying out operational duties overseas.

Philip, 99, was transferred by ambulance to St Bartholomew’s Hospital in the City of London on Monday, having spent nearly two weeks at the private King Edward VII’s Hospital.

The development heightened concerns for the duke, who will turn 100 in June and has now spent his longest period in hospital – 14 nights.

He was said to be “comfortable” after his arrival, with Buckingham Palace saying “doctors will continue to treat him for an infection, as well as undertake testing and observation for a pre-existing heart condition”.

Duke of Edinburgh admitted to hospital
Members of the press outside St Bartholomew’s Hospital (Yui Mok/PA)

The Palace added that the duke was responding to treatment, but was expected to remain in hospital until at least the end of the week.

Philip was shielded from public view with umbrellas as he left for St Bartholomew’s, which is an internationally renowned NHS hospital and home to Barts Heart Centre – Europe’s largest specialised cardiovascular service.

The duke was initially admitted to hospital on February 16 for a few days as a precautionary measure after feeling unwell.

A week later, the Palace announced the Queen’s consort was being treated for an infection.

Duke of Edinburgh admitted to hospital
Staff shielded the exit with umbrellas alongside an ambulance outside the rear of the King Edward VII’s Hospital (Dominic Lipinski/PA)

On Monday, the Palace released video footage of the Queen having a cheery call with the Governor of South Australia as she virtually unveiled a statue of herself – an official engagement which took place last week.

The monarch also has her official papers in her famous red boxes to deal with, as well as other business of state.

The Queen, the nation’s longest reigning sovereign, has been married to Philip for 73 years.

Meanwhile, the Duke and Duchess of Sussex have faced calls to postpone their controversial Oprah interview while the duke is unwell.

Oprah Winfrey interviews Duke and Duchess of Sussex
The Sussexes during their interview of with Oprah Winfrey (Harpo Productions /Joe Pugliese/PA)

Public relations and crisis consultant Mark Borkowski warned that Harry and Meghan are at risk of a “real reputational mess” if they go ahead with the broadcast in the US on Sunday.

Mr Borkowski told the PA news agency: “The timing is just horrendous.

“Anybody who looks at this through the optics of a caring family, even a family who are estranged from one another, it’s very uncomfortable as you edge towards Sunday.”

Philip has been treated for heart problems in the past and in 2011 was rushed to hospital by helicopter from Sandringham after suffering chest pains as the royal family was preparing for Christmas.

In the serious health scare, he was treated for a blocked coronary artery at Papworth Hospital in Cambridgeshire and underwent a minimally invasive procedure of coronary stenting.