THE general election called by Prime Minister Gordon Brown last week will change not just the political make-up of the UK but its geographical identity too.
A review of constituencies by the Boundary Commission for England means the number of seats in the House of Commons this year will rise from 646 to 650.
Harrow borough is directly affected, as its number of seats increases from two to three.
The in-depth review began in 2001, but because of the five-year wait for a general election, its results are only now taking effect. The commission says the changes are necessary to balance population increases.
Consequently, residents in Pinner, Pinner South and Hatch End wards will not now get a chance to re-elect or boot out standing Harrow West MP Labour Co-operative Gareth Thomas.
Instead, they have been moved across to join a new constituency called Ruislip, Northwood and Pinner.
The move may be confusing for voters because the new seat crosses the borough boundary between Hillingdon and Harrow. Whoever wins the contest on May 6 will have the unique problem of dealing with two different unitary councils.
In its guidance on constituency changes, the Boundary Commission says: "Electoral reviews are an important tool in upholding integrity in the democratic process.
"Fairness at local elections, that is, each elector's vote being worth the same as another's, is a fundamental democratic principle."
Evidence, however, suggests this is still not the case in the UK. For example, voters in the Western Isles in 2005 had four times as much influence on the election of their MP as did voters across Harrow, because of the differing populations.
Such problems are inherent in the first-past-the-post system of election, in which losing votes are discarded. In any case, the changes in constituency boundaries mean that otherwise predictable seats will take an unpredictable twist.
Harrow East however, unaffected by boundary changes, is still perhaps the most likely to change colours. It has a population of 89,000.
Current MP Tony McNulty won the seat as New Labour swept to power in 1997, but it had previously been safe for Conservatives since 1970.
Added to the mix are the Lib Dems, who have steadily increased their share of the vote. Harrow East is also likely to attract national interest given the involvement of Mr McNulty in the expenses scandal.
'Wanted' posters targeting the Labour MP have even been printed in national newspapers by the political reform campaign group Power 2010.
Politics.co.uk, a leading political blog, gave its verdict: "The local council is overwhelmingly Conservative, and, as this area was a Tory stronghold for a long time before 1997, it seems a good bet that the Conservatives will look to steal this seat away from Labour."
Meanwhile, voters in Harrow West, where three of the previous 12 wards are lost, have a greater chance of influencing the election than in 2005. The constituency now serves 89,000 people.
Politics.co.uk said of the seat: "The loss of Pinner from the Harrow West constituency will be favourable to Labour at the expense of the Conservatives in the 2010 general election, although this change will probably not be enough to save Labour's small majority here.
"The Conservatives will expect to gain this seat, and a large swing could see them win over 50 per cent of the vote."
The newly formed constituency of Ruislip, Northwood and Pinner, shared with Hillingdon borough, comprises a population of about 90,000 people.
This, perhaps, makes it more unpredictable than previously, although current Ruislip and Northwood MP, Conservative Nick Hurd, will expect to win again.
Politics.co.uk said: "In the light of Labour's current unpopularity it is likely Hurd will re-establish or even surpass the traditionally high Conservative share of the vote, although this may be offset by the growing share held by the Liberal Democrats, who are expected to hold second position as Labour continue to slide."
* Find out how to vote and register at www.aboutmyvote.co.uk .