Don't be so British. Be Australian.

That is the rallying cry from London mayor Boris Johnson to volunteers for this year's Olympics, starting July 27.

Australians have often been derided for their brashness by their British counterparts but London organisers have shamelessly tried to duplicate countless aspects of the 2000 Sydney Games.

Launching the garish pink and purple uniforms for the 8000 London Olympic ambassadors, the eccentric Johnson called on his compatriots to not be standoffish.

"What do you think of the uniform? It's quite striking isn't it. I hope you don't feel too ridiculous," Johnson said.

"You are the ambassadors and you have to greet everybody when they come to London.

"What we need to do is to overcome our natural British reserve and be a little bit more like the Australians."

Johnson's appeal for Brits to follow Australia's example during the 16-day sporting spectacular is a common theme amongst organisers.

London Olympic boss Sebastian Coe wants the capital to reproduce Sydney's party atmosphere and the opening ceremony's artistic director Danny Boyle hopes the spectacle draws comparisons to the 2000 event.

Tom Wald, AAP London Correspondent