The Queen is under medical supervision at Balmoral with doctors concerned for her health, Buckingham Palace has said.

Her immediate family - including Prince Charles and the Duke of Cambridge - have rushed to be by her side at her home in the Scottish Highlands.

A statement by Buckingham Palace said: "Following further evaluation this morning, the Queen's doctors are concerned for Her Majesty's health and have recommended she remain under medical supervision.

"The Queen remains comfortable and at Balmoral."

The monarch, 96, pulled out of a virtual Privy Council yesterday, a day after appointing Liz Truss as PM at her home in the Scottish Highlands.

All of her four children have arrived at Balmoral following the announcement about her health.

An RAF flight landed in Aberdeen shortly before 4pm carrying the Duke of Cambridge, the Duke of York and the Earl and Countess of Wessex.

They arrived at Balmoral shortly after 5pm, with Prince William at the wheel of a Range Rover carrying the three other royals.

Clarence House confirmed the Prince of Wales and the Duchess of Cornwall had travelled to the Queen's home.

The Duchess of Cambridge has remained in Windsor as Prince George, Princess Charlotte and Prince Louis are on their first full day at their new school.

The Princess Royal is also at Balmoral, and the Duke of York and the Earl and Countess of Wessex travelled to the Queen’s Scottish home this afternoon.

And it is understood Prince Harry will be travelling to Scotland by himself after it was previously reported the Duchess of Sussex would be going with him.

Meanwhile, Prime Minister Liz Truss - the 15th of Her Majesty's 70-year reign - says the whole country "will be deeply concerned" by the news from Buckingham Palace.

"My thoughts - and the thoughts of people across our United Kingdom - are with Her Majesty The Queen and her family at this time," she tweeted.

The nation’s longest-reigning monarch has ongoing mobility issues and looked bright but frail and used a walking stick during Tuesday's historic audience with Ms Truss.

It followed a visit from outgoing prime minister Boris Johnson as he tendered his resignation.

The Queen would usually appoint prime ministers from Buckingham Palace or sometimes Windsor Castle - but has been living at Balmoral due to her mobility.

Her Majesty, who celebrated her Platinum Jubilee this year, is on her traditional summer break in the Scottish Highlands, but has faced health issues since last autumn.

She now regularly uses a walking stick, but rallied to appear on the Buckingham Palace balcony for her Jubilee.

Messages from well-wishers have poured in from across Kent following the news.

The Archbishop of Canterbury said "prayers of people across the Church of England and the nation" are with Her Majesty.

"May God’s presence strengthen and comfort Her Majesty, her family, and those who are caring for her at Balmoral," the Most Rev Justin Welby said.

North Thanet MP Sir Roger Gale said: "My thoughts and those of my family are, with those that I am elected to represent I am sure, with Her Majesty the Queen and the Royal Family at what is clearly a time of great concern for Her Majesty’s health."

The Lord-Lieutenant of Kent, Lady Bella Colgrain, also sent her wishes to the Queen.

"We are deeply concerned to learn this news and our thoughts are with Her Majesty and the family at this difficult time," she said.

South Thanet MP Craig Mackinlay says the news is "deeply worrying".

"The thoughts and prayers from myself and all in South Thanet are with Her Majesty The Queen and her family at this time," he said.

Former sports minister and MP for Chatham and Aylesford Tracey Crouch says she was at Chatham Town FC celebrating the Queen's award to the club for voluntary service.

She says the award recognised their "brilliant work in the community" and that "all our prayers" are with Her Majesty.

Meanwhile, Labour Party leader Sir Keir Starmer says he is "deeply worried" by the news from Buckingham Palace.

"My thoughts are with Her Majesty The Queen and her family at this time, and I join everyone across the United Kingdom in hoping for her recovery," he said.

Commons speaker Sir Lindsay Hoyle interrupted the speech of SNP Westminster leader Ian Blackford during the energy debate today.

He said: "I know I speak on behalf of the entire House when I say that we send our best wishes to Her Majesty the Queen and that she and the royal family are in our thoughts and prayers at this moment."

Outside Buckingham Palace, a sign reads: "No Guard Changing ceremony today."

Meanwhile, BBC One has suspended its regular programming to focus on coverage of the Queen.

Newsreader Huw Edwards has taken over the reigns of the broadcaster's special news programme wearing a black suit and tie. The attire is the BBC protocol for serious royal illnesses and deaths.

Heir to the throne Charles was said to have been making regular morning visits to see his mother later in the summer as she continued to struggle with her mobility, with the unplanned visits considered highly unusual.

She missed the Braemar Gathering highland games last weekend, which she usually attends each year.

During her Platinum Jubilee celebrations, the Queen only travelled to Buckingham Palace twice, first for her Trooping the Colour balcony appearance and then for a finale after the pageant.

She secretly spent a night in hospital in October undergoing tests and was then under doctors’ orders to rest for the next three months, missing the Remembrance Sunday Cenotaph service and Cop26 climate change talks.

The Queen caught Covid-19 in February, and suffered from mild cold-like symptoms but said the virus left her “very tired and exhausted”.

Elizabeth II is the first British monarch in history to celebrate a Platinum Jubilee.

Her reign has stretched from the post-war years through a new millennium and into a radically altered 21st century.

In her twilight era, she has been setting her affairs in order, using her Jubilee message to endorse her daughter-in-law the Duchess of Cornwall, once a royal mistress, to be Queen and crowned at the Prince of Wales’s side when he one day becomes King.