Around 80 bikers, many wearing leathers adorned with their service medals, drove into the grounds of the Royal household and parked their vehicles in a long line in front of the house.
Prince Charles posed for photographers in front of the bikes and was even persuaded to sit on one –a Yamaha Venture Star 1300.
As one of the bikers turned its engine on, the Prince gave a look of mock astonishment as heavy metal played from it, and made a joke about the choice of music.
After meeting some of the bikers outside, Charles went inside Clarence House for a drinks reception, where he chatted to more of the branch members.
The event was organised at the Prince’s request after he met some of the bikers at the Wiltshire town of Wootton Bassett in January last year.
The Royal British Legion Riders Branch was founded from an ex-services motorcycle club in 2004 and now boasts more than 4,250 members both in the UK and abroad.
Members of the Riders Branch have been present at more than 100 repatriations and have appointed their own repatriation liaison officer to offer support to families.
Since its creation, the organisation has raised more than £300,000 through various fundraising activities to date.
Bill Haley, 51, who served in the Army for 10 years and is now a police sergeant in Wiltshire, said he met Prince Charles on his visit to Wootton Bassett.
He said: “This was his way of saying thanks to us for all the fundraising we have done.
“He asked us what we thought about moving the repatriations to Brize Norton and I said it wouldn’t be the same.
“I said there wouldn’t be the same atmosphere that there is at Wootton Bassett and he said it was a shame.”