The royal couple spent three days at the Soukya resort in Bangalore, which is famed for its yoga and wellness programmes and Ayurvedic treatments.
Both the King, 75, and Queen, 77, have stayed at the £3000($6500)-a-week resort on several occasions and are said to relish its focus on holistic wellness.
The Queen also eased the journey from London to Sydney with a short stay there two weeks ago.
A Buckingham Palace spokesman said: “Their Majesties had a short private stopover in India to help break the long journey back from Samoa. They return to the UK this morning.”
However, it did chime with medical advice to include appropriate periods of rest as part of the overall long-distance tour planning and to continue to protect and prioritise the King’s continued recovery.
Sources confirmed the Indian spa was well known to the King and Queen and that they had both visited several times.
Royal couple the ‘least demanding’ guests
Soukya, in Bengaluru, boasts a raft of celebrity clientele, including Dame Emma Thompson and the late Archbishop Desmond Tutu.
The renowned holistic centre is run by Dr Issac Mathai, who has been His Majesty’s holistic health consultant for decades and once described the royals as “the least demanding of my guests”.
The daily schedule is said to begin with morning yoga sessions, followed by breakfast and rejuvenation treatments before a healthy vegetarian lunch.
In the afternoon there is a second round of therapies, followed by a meditation session before dinner and lights out by 9pm.
The King and Queen were due to arrive back in London on a commercial flight on Wednesday before the monarch resumes his weekly cancer treatment.
Their 10-day visit to Australia and Samoa for the biannual Commonwealth Heads of Government Meeting, which was by no means guaranteed in the wake of the King’s cancer diagnosis, proved such a success that the palace has already confirmed plans to resume their traditional overseas tour schedule next year.
The twice-yearly tours, which take place in the spring and autumn, will resume subject to medical advice after the Australia trip proved the “perfect tonic” for the monarch.
The King “genuinely loved” the visit and has “thrived” on the schedule, which involved up to 10 engagements per day, a senior palace official said.
He has spoken of his “great love” for the country, borne out of his deep interest in multiculturalism as well as his passion for its age-old traditions of yoga and Ayurveda.
He is said to be a member of The Bhavan, a cultural centre for celebrating Indian art in London, and also enjoys Indian classical music.
Last year, he told British Indian peer Lord Karan Bilimoria at a pre-coronation reception that he was looking forward to making a state visit to India soon.
When he launched an emergency Covid appeal in 2021, the then Prince of Wales recalled his “wonderful visits” to India.
He said: “Like many others, I have a great love for India and have enjoyed many wonderful visits to the country.
“Indian aid and ingenuity have been a support to other countries throughout this immensely difficult time. As India has helped others, so now must we help India.”
It was during the pandemic that the monarch also reflected upon the healing and therapeutic power of yoga, which he described as an “accessible practice” that could help those who had caught the virus.
“By its very nature, yoga is an accessible practice which provides practitioners with ways to manage stress, build resilience and promote healing,” he said.