Nabbed: The yob who used back of Cameron's coat as a handkerchief

This time, the attack was equally childish - but a little more messy.

While Mr Cameron was out on the hustings yesterday, a youngster sneezed into his hand and then wiped it down the back of the Tory leader's jacket.

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Mr Cameron made light of the incident in Hastings, East Sussex, peering over his shoulder and saying: "That's one of the joys of my job. I'm sure I'll be fine."

But a nearby police community support officer collared Kingsley Cardi, 15, and issued him with a caution for anti-social behaviour.

Afterwards Cardi, an aspiring musician, said: "I sneezed in my hand and wiped it on him. It was just a joke - I was showing off.

"They asked me to apologise to David Cameron, but in the end his security would not let me near him again."

Mr Cameron was in the seaside town canvassing support for the Tories in next month's local elections, buying a pot of jellied eels and packet of lemon bonbons during his walkabout.

Cardi, from nearby St Leonards, pounced outside the Priory Meadows shopping centre around 3pm.

An onlooker said: "It was unbelievably cheeky. The young lad sneezed loudly into his hands as he walked behind Cameron and wiped it all over the back of his jacket.

"Mr Cameron checked his back and couldn't believe it, but tried to stay composed as he was hoping to win people over."

Cardi, who says he has been expelled from two schools, lives with his mother Daisy, 46, who is unemployed, and father Nick, 48, a retired disc jockey, in a ground floor flat in nearby St Leonards.

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Last night he said: "I'd only seen David Cameron twice before on television and the only thing I really knew about him was that he had a bad haircut.

"I felt really bad about what happened, because it looked like an expensive suit.

"I would be really annoyed if someone did it to me.

He said he is underprivileged compared to the Tory leader.

"I would not say he is a toff, but he has been very lucky in terms of his opportunities because he's been born into money and I haven't.

"I don't think I'll be Prime Minister one day, but he's got a good chance."

He said his musical and fashion inspiration is the junkie singer Pete Doherty.

"But I don't like all his drug taking."

Cardi said he has nothing against the Tories, but will not be voting for them when he reaches 18.

He is "Green Party through and through".

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He added: "I expect I'm going to have to do loads of washing-up - or get grounded and miss loads of parties - because of this."

The teenager has a Myspace entry which tells how he likes to play "acoustic-folk-indie" music with a male friend called Misha Tyson.

Last night Tyson's mother Sharon, 40, defended Cardi. "I have heard about what happened and all I will say is that Kingsley is not a troublemaker," she said.

"He is a bright lad and is an intelligent young man."

A spokesman for Mr Cameron said no damage was done to the Conservative leader's jacket.

In February last year, Ryan Florence, 17, brandished an imaginary gun at Mr Cameron during the politician's visit to Manchester.

Florence, clad in a black hoodie, pretended to shoot the politician and later boasted about guns, drugs and his criminal record.

Several weeks later, he was sentenced to 18 months youth custody for three burglaries.