Susanna Reid and Rylan Clark are among the famous faces wishing the Queen well, following a rare announcement the monarch is under medical supervision with doctors 'concerned' for her health.
The 96-year-old pulled out of a virtual Privy Council on Wednesday, a day after appointing Liz Truss as PM at her home in the Scottish Highlands.
The Queen's close family including the Prince of Wales are joining her at Balmoral, and The Duke and Duchess of Sussex have cancelled their event this evening to go to Scotland.
Well-wishers from around the world have expressed concern, including celebrities.
Radio and TV presenter Rylan reflected on the Queen's many years of service, writing on Twitter : "Whatever you think of the monarchy our queen has give her life serving this country. What a woman. God bless her," finishing his post with a love heart.
Good Morning Britain presenter Susanna Reid wrote: "No one more likely to be so loved, admired and respected than Her Majesty The Queen and although she cannot be immortal, I think we have always hoped she might be."
Like Rylan, Susanna finished her touching post with a love heart.
Sharing a smiling photo of the Queen, singer Peter Andre simply wrote on Instagram : "Praying for our Queen," followed by the emojis of a preying hands and a black love heart.
TalkTV host Piers Morgan shared a picture of of the Queen from Tuesday on Twitter, simply captioning it with the praying hands emoji, later writing: "I can't even imagine Britain without this Queen. Very unsettling day."
Love Island star Chris Hughes also took to Twitter to send his best wishes, writing: "Sending thoughts Your Majesty", ending his post with a love heart.
Royal fans are beginning to gather outside the gates of Balmoral and other royal homes amid concern for the Queen.
Taxi driver Phillip Elias, 76, from London said: “Let’s hope she pulls through.
“I’m old enough to remember the assassination of JFK and the funeral of Winston Churchill. This would be much bigger than those.”
Wasim Younis, 53, and his wife Samina, 50, had travelled down from Burnley, Lancashire for a family graduation.
He said: “we’ve just heard the news. Let’s hope the Queen’s health improves soon.
“The whole country will want that.”
Hungarian Matt Varga, 33, works as a head of security in London. His mum Erika, 60, is visiting him and they were visiting Buckingham palace.
He said: “We would like to wish the Queen all the very best. We hope her health improves very soon.”
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, which followed a visit from outgoing prime minister Boris Johnson as he tendered his resignation.
A Buckingham Palace spokesperson said earlier today: "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."
