Analysis By Karen Allen BBC News health correspondent

Labour promised to radically restructure the health service

If a year is a long time in politics, just 24 hours can be an eternity in the health service. Every 24 hours the NHS treats nearly a million people.

The public perceptions of how the health service is faring will be a huge influence on how votes are cast.

With health spending having tripled in the past 10 years, voters will be asking if the investment has paid off.

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When Tony Blair entered Number 10 his party promised to slash waiting lists; recruit more staff and radically restructure the health service - putting patients first. So has Labour delivered?

Study the figures and you'll see that waiting times for treatment have been reduced - at least in England.

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Labour is likely to meet its target that no one should wait more than 6 months for an operation, although it is lagging behind in other nations.

But there's a problem in the way hospital waits have been defined. Patients aren't included on the waiting list until a consultant decides they need treatment.

This is the so called "wait for the waiting list" which the Liberal Democrats have seized upon as their main pre-election mantra.

So the statements by ministers that waits for treatment have fallen only explain part of the picture.

It is true that Labour has conceded that delays for tests and scans have led to a distortion of the figures, and so it is changing the way patient waits are counted.

Waiting times

It has promised that from the moment a patient's GP refers them for treatment to the time of their operation, no one should wait more than 18 weeks by 2008 in England..

It is a bold promise - with a nice sense of symmetry when contrasted with the 18 month waits that some patients experienced back in the mid 90's.

But the big question is this: With huge shortages in radiologists, radiographers, haematologists and other "backroom staff", how will this impressive target be achieved without causing major clinical distortions?

While political opponents claim the target culture of the NHS under Labour has skewed clinical priorities, Tony Blair's party would argue that it has given focus to its healthcare reforms, and provided incentives for the best performers in the health service to win greater freedom and less meddling from Whitehall.

Many of the changes Labour has brought to the NHS are structural: for example, foundation hospitals; the creation of primary care trusts and greater use of the private sector.

Many of these structural changes, however, do not apply in Scotland and Wales, where Labour-led administrations have taken a more traditional path.

Margaret Dixon's operation was repeatedly cancelled

But voters are likely to make judgements on their own experiences.

The recent case of Margaret Dixon whose shoulder operation was cancelled seven times, will have some resonance for anyone who has ever had to undergo surgery.

But does one patient's experience tell the full story?

The figures show that between 1998 and 2004 there's been an 18% increase in cancelled operations in England- and although there is now more demand on the health service, with growing numbers of patients coming through the door, the number of operations cancelled has increased faster than the numbers of surgical procedures being carried out.

So what are the parties offering ?

More choice

In England, Both Labour and the Conservatives are promising the electorate more "choice".

Under Labour, patients will be able to select from a list of up to five or six hospitals (including a private one) for treatment.

The pledge is to make this an unlimited choice by 2008, so long as the private provider is charging the equivalent of the NHS rate.

Meanwhile the Conservatives claim it is their party which offers real choice, going one step further than Labour.

Its voucher system - once called the "patient passport" - would enable patients to shop around for treatment and if a private provider charges above the NHS rate, while the government would foot half the bill with the patient having to pay the rest.

It is a complicated concept - not least because the boundaries of private and public healthcare have become blurred - so the Conservative party has focused its health campaign on an issue that is easier to fit in a headline.

The Tories say hospital superbugs are out of control

With hospital "superbugs" responsible for five thousand deaths a year, the Conservatives claim that despite the extra billions Labour has committed to the health service, it's a problem that's spiralled out of control.

They have promised to give matrons the power to close down dirty wards. Labour says matrons can do that already.

For the Liberal Democrats the Choice Agenda is a bit of a red herring.

Patients, they argue, want to get treated promptly and conveniently - they don't want to have to shop around.

So their promise is to concentrate on what they see as the "real" issues - such as free personal care for elderly people, free eye and dental checks and unblocking the bottlenecks that cause those "hidden waits".

They also say they would concentrate on tackling causes of ill health, such as poverty, pollution, poor diets and smoking.

Scotland and Wales

Health is the responsibility of the Scottish Parliament north of the border and the Welsh Assemby in Wales.

But despite devolution, it is likely to be a major political issue in the General Election.

Waiting times are of particular concern in Wales, where they are longer than in England, and the ruling Labour Party is only pledging to cut waiting times to 26 weeks by 2009.

Public health issues like smoking, obeisity and damp housing are also bigger concerns in these two nations.

Looking towards the future, there could be further debate on whether English-style NHS reforms will be implemented by the devolved governments.

Scotland is already distinctive in one key area.

People in nursing homes do not pay anything towards their care, following a decision by the Scottish Parliament.