Britain’s Prince Philip, the Duke of Edinburgh, posed with his wife, Queen Elizabeth II, at Windsor Castle on Tuesday, one day before he celebrates his 99th birthday.
The pair plan a quiet lunch at Windsor Castle, where they have been socially isolating because of the Covid-19 pandemic.
Prince Philip is now by far the longest-serving consort of any British monarch.
The rest of the royal family will send their best wishes to him on video calls.
"I haven't seen my father for a long time," Prince Charles, heir to the throne and the eldest of Prince Philip's four children, told Sky News last week.
"He's going to be 99 next week. Facetime is all very well. You really want to give people a hug."
The royals make little fuss about their birthdays in public but this year celebrations have been even more muted.
Traditionally, the prince's birthday would be celebrated with gun salutes in London.
But with social gatherings banned, the queen felt such royal ceremonies would be inappropriate and also cancelled tributes for her own birthday in April for the first time in her 68-year reign.
But Buckingham Palace did release a new photograph of the royal couple, taken last week inside Windsor Castle, to celebrate the prince's birthday.
Britain is still under coronavirus restrictions that limit the size of gatherings, and Prince Philip and the queen, 94, are well into the age most vulnerable to Covid-19.
Prince Philip married the future queen at Westminster Abbey in 1947 when she was 21 and he was 26.
Together they had four children – Charles, the Prince of Wales and heir to the throne, Anne, Andrew and Edward.
Prince Philip stepped down from royal duties in August 2017 after completing more than 22,000 solo engagements, but in recent years he has been rarely seen in public.
He broke retirement silence in April to issue a statement thanking those involved in the fight against the coronavirus pandemic.
