Eating your own vegetables is incredibly special, said the Queen as she spoke about how she loves gardening at Highgrove House.

She praised the virtues of tending to the 18-year-old vegetable patch at the King’s private Gloucestershire home, describing it as “a wonderful way to pass the time”.

The Queen was speaking to elderly residents at St John’s Foundation almshouses in Bath during a visit to mark the group’s 850th anniversary – her third official engagement in as many days.

She also offered another update on the King’s health following his three-night hospital stay to treat an enlarged prostate, telling one well-wisher: “Yes, he’s recovering well, thank you”.

The King was discharged from the London Clinic on Monday and flew by helicopter from London back to Sandringham on Wednesday, where he will continue his recovery.

Although he will continue much of his office-based work, he is not expected to return to public duties for at least a fortnight.

The Queen, who has been patron of St John’s Foundation since 2009, chatted to residents over tea and cakes in a quiet courtyard in Bath city centre.

As the group engaged in a lively discussion about the benefits of gardening, Camilla said: “It gets everybody outside, I find it the most relaxing thing in the world, you come in and everything starts stiffening up. It’s worth it.

“There’s something very satisfactory about Highgrove’s 18-year-old vegetable patch. It’s a wonderful way to pass the time.”

She added: “Eating your own vegetables is incredibly special”.

The Queen has often spoken about her love of gardening as a form of therapy.

The 4.8ha garden at her own private home, Ray Mill, in Wiltshire, features a wildflower meadow, an orchard, beehives, and a large pond.

When talking about other types of exercise, the Queen told 77-year-old Joanna Laurence: “I can recommend Silver Swans ballet for older people, the first one I ever came to was in Bath. You ought to try it, it’s wonderful.”

She then walked the short distance from the almshouses to Bath Abbey for a service to celebrate the foundation’s anniversary.

She was greeted by almost 900 children from seven primary schools that are supported by the fund.

Ben Fletcher, chairman of St John’s Foundation, said after the service: “Because we’ve been here for so long, St John’s is really woven into the city and I think what it ultimately gives is a degree of comfort”.

“If you really need help beyond what can be provided by the Government or the local authority, St John’s is there, we are the last line of defence for people in greatest need.”