The British election race will be tighter than expected. And New Zealand may yet have a footnote in the outcome

Not long ago, they looked like they would walk it. Rupert Murdoch rarely backs a loser, and his Sun newspaper's surprisingly early abandonment of New Labour and declaration of support for David Cameron's Conservatives – a vicious arrow fired at an already wounded Labour party as they gathered in Brighton for last September's party conference – underlined the advantage.

Back then, the Tory lead hovered around 15 points. In recent months the gap has closed enough to test many Conservatives' circulation.

The most recent polling sends mixed messages. The headlines of Tuesday morning's polls, as PoliticsHome.com puts it, read like this: "A YouGov/Sun poll has given the Conservatives a 10% lead over Labour. The Tories are on 41%, the first time they have been over 40% since early January. Earlier an Express/Opinium poll also gave the Conservatives at 10% lead over Labour while an ICM/Guardian poll put the lead at only 4%."

I'm no psephologist, but I do know that the Conservatives will be sweating at the ICM result, not least because it's proved sharper in the past than its polling adversaries.

Why three polls on the same day? Well, barring some cataclysmic bit of news to dissuade him, Gordon Brown will head for Buckingham Palace today to ask the Queen if she wouldn't mind dissolving parliament. This bit of ritual will formally fire the starter's gun for an election on May 6.

You could be forgiven for thinking that the election campaign had already begun. The last week has witnessed a flurry of speeches, announcements and snarls from all sides, as well as a guest appearance from Tony Blair – remember him? – who was tempted back from his globetrotting projects (you know the ones: reversing climate change, peace between Israelis and Palestinians, religious harmony among all peoples, and a few high-powered commercial consultancies) to sing the curses of the "centreless" Conservative party.

There is a clear risk for the Labour party in dragging Blair-of-Iraq back to the stump, but there's no doubting he articulated the Conservative weaknesses as well as anyone has to date.

No prizes for guessing that it will be the economy, however, that will dominate. A debate of the would-be chancellor's last week was pored over by political journalists, who were particularly interested in whether George Osborne had set himself a banana skin earlier in the day, when he announced that the Tories would repeal Labour plans for a one percent increase in National Insurance contributions.

How absurd, the critics cried, to at once be calling for public spending to be slashed, for the deficit to be scythed, yet cutting tax. Osborne survived the debate, if unspectacularly. The Lib Dem financial whizz, Vince Cable, predictably was judged to be the debate's winner, with Alistair Darling, the chancellor incumbent, coming second.

This tax question will rumble on. Osborne's call for a rowback on the Labour NI (National Insurance) rise seems to have had some traction; just when it was looking sticky for him, a phalanx of business leaders helpfully wrote a letter to the Daily Telegraph pouring praise on the policy. The Tories now are having a go at Brown for his steady rises in NI over the years – a "tax on jobs", “Gordon Brown’s favourite stealth tax”, they charge, and not without cause. Labour's riposte centres on their management of the economy through the turbulence of the crisis, set against the innocence and inconsistency of Osborne.

Where Gordon Brown looked down and out some six months ago, the contest today is very much alive. It's tight enough that talk of a hung parliament has been everywhere – sparking something of a scramble to come up with a plan to avoid dragging the Queen into a constitutional scrum.

The upshot is that New Zealand may yet have a footnote in the history of the UK 2010 election. The cabinet secretary, Gus O'Donnell, is in Aotearoa to swot up the cabinet manual.

The drafting of a similar document in Britain, one constitutional expert says, "could be as important for good government as a written constitution. In New Zealand, where they have had a similar manual for over 30 years, there is strong acceptance that what the manual lays down are the rules of the political game."