Phil Collins, Rod Stewart party at Buckingham Palace

Phil Collins and Rod Stewart partied with King Charles III at Buckingham Palace.

The music legends were invited to celebrate the 50th anniversary of The King's Trust at Buckingham Palace on 14 May.

Genesis singer Phil, 75, who has notably suffered an array of health complaints in recent years, made a rare appearance on crutches.

He was accompanied by his ex-wife Jill Collins, 70, who noted the occasion with a lengthy Instagram post describing their experience at the elite, but soggy, garden party.

"Despite the downpours of torrential rain which did not seem to dampen the festivities @officialphilcollins and I were very proud and honored to be there and have a few private moments with King Charles," she wrote in a caption accompanying a gallery of event pics.

She added the King "seemed genuinely pleased to see Phil" and explained her ex-husband had been the Trust's first official ambassador four decades prior, as well as a longtime trustee.

She went on to mention they had been able to catch up with fellow musician Sir Rod Stewart, 81, and his wife, Penny Lancaster, 55.

"We ran into @sirrodstewart and @penny.lancaster among other old (in the nicest sense of the word) friends," Jill wrote.

In January, Phil gave a health update to explain his various chronic ailments, many of which stemmed from longtime alcohol abuse as well as a series of falls that left him needing at least five knee surgeries.

"It's an ongoing thing," he told interviewer Zoe Ball as part of the BBC Two TV special Phil Collins Eras: In Conversation.

"I have a 24 hour live-in nurse, um, to make sure I take my medication as I should do. Uh, I've had challenges with my knee - I had everything that could go wrong with me did go wrong with me. You know, I mean, I got COVID in hospital, my kidneys started to back up... You know, everything that start, that could all seemed to sort of converge at the same time."