Their Royal Highnesses were joined by supporters of the charity including Yasmin and Amber Le Bon – who are taking part in the race – as well as Joanna Lumley, Sire Evelyn and Lady de Rothschild.
The race, which will see a group of 30 rickshaws travel across a 500-mile course in India in support of the Asian elephant, will take place in November.
The Prince and The Duchess became Joint Presidents of the conservation charity in 2014. It was founded by The Duchess of Cornwall’s late brother Mark Shand.
Their Royal Highnesses accepted an award (Conservationist of the Year) that was presented to Mark Shand in 2014.
The award (a specially commissioned glass rhinoceros sculpture) was from the Perfect World Foundation run by Swedish conservationists, Mr. and Mrs Lars Jacobsson.
Their Royal Highnesses also met the Indian High Commissioner, His Excellency Mr. Ranjan Mathai and his wife Mrs Gita Mathai.
The Prince was hosted by Ben Elliot, from the Quintessentially Foundation and The Duchess by Ruth Powys, Chief Executive of Elephant Family.
Both Ben and Ruth also spoke at the event. Ben drove Their Royal Highnesses around the Clarence House garden in one of the rickshaws, which was painted in the union jack and the Indian flag.
At the end of the reception The Prince of Wales made a speech, during which he said: "I just wanted to say when this terrible tragedy occurred last year and we lost Mark, both my wife and I said at the time that we must keep his legacy going. So both of us could not be more proud to become joint presidents of Elephant Family.
“I can only wish all of you every possible success in driving these machines on rather bumpy roads I suspect. I suspect they don’t have very good suspension so be even more careful. Good luck ladies and gentlemen and thank you for all your support.”