Jonathan Reed: The warm-up is over as leaders fight for a place in the sun

Two-and-a-half years ago, he considered calling the election but

decided against it in the face of a Tory surge in the polls. Given the Tories have finally found a bit of bounce in the opinion polls in recent days, he may have wished to have delayed again. This time, however, the constitution didn't offer much flexibility – polling day has to be held by early June.

Like John Major in the 1990s, he has waited just about as long as he could before hearing the verdict of voters. At last, the warm-up is over and yesterday the three main party leaders could not wait to get out of the starting blocks.

With the sun showing London at its best, David Cameron was first out for an early morning jog to blow the cobwebs away. While Mr Brown headed to Buckingham Palace to ask the Queen to dissolve Parliament, Mr Cameron was arriving at County Hall, a stroll across Westminster Bridge from the Houses of Parliament, to rally his troops.

Surrounded by around 200 candidates and largely youthful party activists on a roof terrace, with Parliament providing a symbolic backdrop, he branded the coming contest "the most important General Election for a generation" and won the biggest cheer when he told them: "You don't have to put up with another five years of Gordon Brown."

With wife Samantha looking on, he was given a final ovation as he struck an optimistic note, declaring: "Let's win this election for the good of the country that we love."

Minutes later, and a few hundred yards away, Mr Brown emerged from the front door of Number 10, having returned from the Palace, to announce

in a serious tone: "The Queen has kindly agreed to the dissolution of Parliament and a General Election will take place on May 6."

Flanked by the rest of his Cabinet – the image of the Prime Minister as team player somewhat at odds with how he fought so fiercely to wrestle the keys to Number 10 from his predecessor – the message of "more of the same" was very different from Mr Cameron's call for change. It was also noticeable that Mr Brown kept Chancellor Alistair Darling close by his side, keen to make the most of the man he wanted to oust from the Treasury just a few months ago.

"Britain is on the road to recovery and nothing we do should put that recovery at risk," said Mr Brown, setting out his theme for the

campaign.

In another corner of Westminster, at Liberal Democrat headquarters, which are just a stone's throw from Parliament, Nick Clegg invited in the cameras as he rallied a small gathering of party officials and rehearsed his own campaign battlecry: "This is not a two-horse race between the two old parties, Labour and the Conservatives. People have got a real choice this time and I think that's why this election is wide open. All bets are off."

And so, opening shots fired, it was time for the great Westminster exodus. Innocent passengers and shoppers at St Pancras Station found themselves confronted by the Prime Minister and his wife, Sarah, marching through en route to catching a train to Kent where he ticked off the first marginal constituencies of the campaign with a trip to Morrisons.

Mr Cameron gave the Tory battle bus its first outing as he headed for Birmingham and then Leeds, a demonstration of just how important Yorkshire is to his chance of gaining power, while Mr Clegg made Watford his first calling place.

This election is well and truly under way – the question now is who will be first to cross the line on May 6.

Jonathan Reed is the Yorkshire Post's political editor