The message comes shortly after William and Catherine appeared at Wimbledon with their two eldest children, Prince George and Princess Charlotte. The Wales family will no doubt soon be looking ahead to their summer vacation as the royal children have now finished school for this academic year.

The image shows the Queen looking relaxed and wearing a turquoise dress in a Liberty fabric printed with a rainforest of toucans, lemurs and monkeys. Last year, Camilla was on duty on her birthday, attending the State Opening of Parliament at the King’s side.

This year, she is said to be spending the day privately. The King, who is still being treated for cancer, is known to have been buoyed by his wife’s support since his diagnosis last year.

The pair celebrated their 20th wedding anniversary at the start of April and have had a busy run of engagements, including hosting a state visit by the French president last week, ahead of their upcoming annual summer break to Scotland.

In the birthday portrait taken by photographer Chris Jackson earlier this month, Camilla can be seen wearing gold drop earrings, a delicate gold bracelet, a gold ring composed of circular plaques on her pinky finger, her wedding band and her five-carat emerald-cut diamond engagement ring as she places her hands together while resting on the gate.

On Wednesday, the Queen was gifted a roll of clingfilm for her birthday in a special holder when she visited a nuclear-powered submarine in Plymouth.