The princes will host a royal reception for FIFA executive committee members at the World Cup in South Africa next month in support of England's 2018 campaign.

Prince William is president of the FA and he and Harry will attend England v Algeria in Cape Town before hosting the reception in Johannesburg the following evening.

The event should come as a major boost to England 2018, and emphasises their efforts to do it by the book rather than get their hands dirty via political deals and back-scratching.

FA and bid chairman Lord Triesman insists it is a strength to be regarded as super-clean.

The failed bid for the 2006 finals was scuppered after England were accused of reneging on a gentleman's agreement to let Germany run for the tournament, and Triesman said there will be no such repeat this time.

Triesman said: "I don't believe you can ever be too clean, I don't mean you should not fight hard or be politically unrealistic but I have said from the beginning that we would not try to earn this by means we would be ashamed of, we simply wouldn't do it.

"I think that's helpful to us. When people say to us 'you're all very gentlemanly and play by the rules' I'm afraid I can't take that as a criticism, I would rather people knew we did it the right way and I believe we will succeed from doing it that way.

"People right around the world want to see it won in the proper way."

The reception to be hosted by the princes should provide extra stardust to the bid which already has David Beckham handing over the candidate file to FIFA president Sepp Blatter in Zurich on Friday.

England 2018 have compiled a 1,752-page document, weighing 8.5kg, which details the vision and technical aspects of the bid from stadia and training bases to fan parks and security.

Beckham will be accompanied by Triesman and England 2018 chief executive Andy Anson, plus two others yet to be confirmed.

With last week's general election failing to produce a new Prime Minister - at least in the short term - there will be no politician in the party but Triesman said he hopes to bring FIFA president Sepp Blatter to meet the new man at number 10.

Beckham's presence will be much more valuable, he said, adding: "He's perhaps the most iconic footballer in the world. He's one of the few people that if he suddenly appeared in any village in the world everyone would know who he was.

"It's right that it should be presented by a footballer because the World Cup is a football festival."

Triesman also insisted he was not concerned about any adverse effect on the bid of recent crowd trouble at lower league matches - FA investigations are under way into incidents at Sheffield Wednesday, Luton and Burton Albion.

The 2006 bid was nearly abandoned after hooliganism at Euro 2000 but Triesman has no fears for next month's finals.

He said: "Over the last 15 years broadly speaking the record of English fans has been as good or better than anyone.

"The record of our fans' behaviour at World Cup tournaments is good, and overwhelmingly for all our qualification games when we have been on the road and when English clubs have been on the road, there has not been trouble."

Each country must present their candidate file to FIFA on Friday, with technical inspections due between July and September, and the final vote by FIFA's executive committee on December 2.

It is expected that 2018 will go to Europe where Russia plus joint bids by Spain/Portugal and Holland/Belgium are up against England.

The other countries expected to fight it out for 2022 are Australia, USA, Qatar, Korea and Japan.

Lord Triesman added: "We're extremely honoured that Prince William and Prince Harry will be supporting England's bid to host the FIFA World Cup while in South Africa.

"As President of the FA, Prince William is a firm advocate of the bid and we're delighted that both he and Prince Harry will be supporting us during the summer."