Prince Harry won't get married for a long time.

The third-in-line to the British throne was the best man at his brother's wedding to Catherine Middleton in April, but Harry - who has been involved in an on/off relationship with blonde South African lawyer Chelsy Davy for seven years - has no plans to follow his sibling down the aisle any time soon.

During a tour of London's Royal Hospital Chelsea's infirmary, Harry was asked by 85-year-old army veteran William Titchmarsh if he would get married soon and answered: "Not for a long time. Who put you up to ask me that?"

Harry, 26, also watched the annual Chelsea Pensioner's parade, where 300 elderly vets marched and gave military salutes during his visit, and took the opportunity to poke fun at his 28-year-old search-and-rescue pilot brother.

"I find it terrifying that your drill is so much better than my brothers', but it doesn't surprise me," Harry said.

"The Army, for me and thousands like me, is a family. In that respect, for veterans coming here, it must be like coming home. That is why this place matters, and always will."