The Queen brought a splash of colour to an otherwise grey and rainy day on her 71st wedding anniversary as she was shown how technology was shaping the future.
Visiting the Royal Institution of Chartered Surveyors in London to mark its own 150th anniversary on Tuesday, the Queen heard it was good to see how the "two institutions of chartered surveying and marriage continue to thrive".
Wearing a cerise pink double-breasted coat and dress by designer Stewart Parvin, a matching Rachel Trevor Morgan hat and a gold, diamond and ruby brooch, the Queen was shown how technology was helping surveyors "build the future".
The monarch, who was a 21-year-old princess when she married the dashing Lieutenant Philip Mountbatten at Westminster Abbey on November 20 1947, also locked a Penfold Letterbox time capsule at the end of her visit, which will be reopened on the institution's 200th anniversary.
She was also given a miniature version of the letterbox made from Lego as a gift.
John Hughes, the institution's president, said: "On behalf of every chartered surveyor in the room and joining us online, may I offer our congratulations.
"It's good to see that the two institutions of chartered surveying and marriage continue to thrive."
On her guided tour the Queen commented on the speed of a virtual train showing the journey of the High Speed 2 railway, earning laughs from onlookers.
The Duke of Edinburgh, who has retired from public duties, did not attend the event and it is likely the couple will be reunited in private later on Tuesday.
Their enduring relationship has lasted the longest of any British sovereign, and Philip has been at the Queen's side throughout the decades, supporting her as she devotes herself to her role as head of state.
It was in 1939 that Princess Elizabeth was said to have fallen for Philip as a teenager.
The distant cousins had been at the same gatherings on a number of occasions, but had their first publicised and pivotal meeting at the Royal Naval College in Dartmouth, Devon, in July that year when King George VI and Queen Elizabeth visited with their two daughters.
Blond-haired, athletic 18-year-old Philip caught Lilibet's eye as he entertained her by jumping over tennis nets.
The king's official biographer, Sir John Wheeler-Bennett, recalled: "This was the man with whom Princess Elizabeth had been in love from their first meeting."
Eight years later, the princess walked down the aisle, dressed in an ivory silk Norman Hartnell gown, decorated with 10,000 seed pearls, glittering crystals and an intricate 13ft star-patterned train, to marry 26-year-old Philip, who was fresh from serving in the Royal Navy in the Second World War.
Within five years, the princess had acceded to the throne.
Their 71-year-union is seen as a key source of stability within the monarchy.
On their golden wedding anniversary in 1997, the Queen paid a touching tribute to her husband, saying: "He has, quite simply, been my strength and stay all these years."
Philip used the occasion to praise the Queen for her tolerance.
"I think the main lesson that we have learnt is that tolerance is the one essential ingredient of any happy marriage," he said.
"It may not be quite so important when things are going well, but it is absolutely vital when the going gets difficult.
"You can take it from me that the Queen has the quality of tolerance in abundance."