NICOLA Sturgeon and Alex Salmond are exuding the "whiff of arrogance" and have been warned not to count their chickens before they are hatched on May 7 as they did in the independence referendum last September.

So said Nick Clegg as he arrived in his large orange and lemon battle-bus in the leafy London suburb of Surbiton; a seat held, thus far safely, by his Cabinet chum Ed Davey, the Energy Secretary.

As the Deputy Prime Minister alighted from the coach, he was greeted by 100 or so beaming Lib Dem activists but also by a small gaggle of protesters, one of whom started to barrack the party leader through a megaphone. "Nick Clegg lied to me, he said Uni would be free!"

By the time the party leader had reached the sanctuary of the family-friendly Grove beer garden, the loud-mouthed heckler had been silenced, allowing the DPM to sit down with mums and chat happily about childcare and maternity leave.

As the Easter sun beat down in a very English setting, the DPM touched on Scotland, where some polls place his party on a life-threatening two per cent.

Mr Clegg insisted the picture in Scotland was more complex than some would like to believe.

If people scratched beyond the headlines and a "lot of self-congratulatory hype of Nicola Sturgeon and Alex Salmond", they found voters were uneasy about how the SNP had taken their eye off the ball on delivering local services.

He suggested Ms Sturgeon and Mr Salmond, who is trying to re-enter Westminster by winning Gordon, were guilty of hubris.

Claiming the SNP were in the habit of "over-hyping themselves", he said: "In the referendum they got the red carpet out, they had the jet ready for Alex Salmond's lofty flight round the nation. They counted their chickens before they hatched and we as Liberal Democrats have an old-fashioned belief...you shouldn't take any vote for granted."

He added: "There is just this whiff of arrogance about the SNP and their tendency to take their eye off the ball from the local services and the local public service people want from their MP."

With that, Mr Clegg put on his jacket and headed along a line of supporters back to the battle-bus. Out in the street, Mr Megaphone had returned: "Clegg says cut back, we say fight back. Everyone hates you."

As local supporters tried to drown out the heckler with chants of "Well done, Nick", the party leader gave one last, large grin and a wave before he disappeared into the air-conditioned shade of the battle-bus.

Next stop, Bath and the continuing task of saving the Liberal Democrats from electoral oblivion.