Charles said it was an uphill struggle for years to get people to share his concern about the climate.
Republic, the campaign group, says environmental issues are still political because they are dealt with by governments.
Titchmarsh is a friend of Prince Charles and has previously said he is loyal to him.
In 2019, the Queen helped make puddings with her son and now they have been distributed and eaten.
Charles and Camilla are both 72, so will be vaccinated in an early part of the rollout, but still face a wait.
The Prince of Wales recorded a message for the Royal British Legion's annual Remembrance Service.
Charles has been interviewed by Edward Enninful about sustainable fashion.
Charles Spencer says the BBC has not apologised for the forged bank statements used in landing the interview with Diana.
Prince Charles recorded two versions of his 1994 interview, a new documentary reveals.
Some of Charles's letters are up for auction and show how he felt after his 1994 interview with Jonathan Dimbleby.
Andrew Marr said Charles could be a good king but will have to put his personal views to one side.