The Queen travelled to Maidenhead on Friday to officially open the new Thames Hospice building.
Her Majesty was carrying out a rare joint engagement with her only daughter, Princess Anne, as they made the poignant visit just before midday.
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The 96-year-old monarch, who made the quick 15-minute drive from her home Windsor Castle, appeared in high spirits as she braved the heatwave wearing a cream and blue floral dress.
Anne, meanwhile, was typically elegant in a striped yellow dress.
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The Queen visited Thames Hospice on Friday morning
The royals were given a warm welcome at the hospice, which provides palliative and end-of-life care to people aged 16 years and over across East Berkshire and South Buckinghamshire.
The hospice, which has been running for more than 30 years, provides nursing, medical and therapeutic care to support the physical, social and emotional needs of patients and their loved ones.
She met with staff and volunteers during the tour
Their services are free of charge, relying on generous donations as well as the time and effort of 700 volunteers.
During the tour, the Queen and Princess Anne met with staff and volunteers and in one particularly poignant moment, the monarch was introduced to one hospice patient.
The royals were presented with beautiful posies
She met Graham White and his wife Pat, who has stage four cancer and is receiving respite care. Just as the Queen was being introduced to the couple, Graham's phone went off, leaving Her Majesty to remark: "Typical, a phone goes off immediately".
Mrs White, 63, sat as she chatted to the Queen and later described the meeting as "very emotional", saying: "This is a memory that I will treasure." Of her husband's phone ringing, she joked: "I could have killed him! People think the Queen is all stiff upper lip but she has a sense of humour."
Graham, who explained his son had rung him, added: "I turned my wife's phone off and I could have sworn mine was off – that was a bit embarrassing."
The Queen was introduced to one hospice patient during the poignant engagement
Before leaving the hospice, she officially unveiled the plaque with her daughter Anne at her side and also signed the visitors' book.
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Earlier this week, the Queen held a special audience at Windsor Castle with her eldest son and heir, Prince Charles, as she presented NHS representatives with the George Cross – an award that acknowledges outstanding actions by civilians and military personnel, not in the face of the enemy.
Her Majesty appeared in great spirits
Despite her ongoing mobility issues, the Queen was photographed without her walking aid.
In a heartfelt statement, she said: "It is with great pleasure, on behalf of a grateful nation, that I award the George Cross to the National Health Services of the United Kingdom.
Before leaving, she unveiled a plaque
"This award recognises all NHS staff, past and present, across all disciplines and all four nations. Over more than seven decades, and especially in recent times, you have supported the people of our country with courage, compassion, and dedication, demonstrating the highest standards of public service. You have our enduring thanks and heartfelt appreciation."
The Queen also signed the visitors' book
The Chief Executives of the National Health Services of England, Scotland, Wales and Northern Ireland were accompanied by a frontline worker from each of the Home Nations. The Queen bestowed the awards before meeting representatives from each nation.
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