Since the seat was created in 1945, it was always a very safe Conservative seat, but In the dark days of the 1997 general election, Harrow West was the safest Conservative seat lost to Labour, with the eighth-highest swing in the country (17.5% to Labour), making it a key 2001 marginal. Labour's immigration policies helped, as Harrow West has a large number of immigrants, who all voted for Blair, making Harrow West one of only a few seats to swing to Labour in 2001 (5.4% swing to Labour, against a national trend of 1.8% swing to the Conservatives). In 2005 Harrow West was less anomalous, with a swing of 4.5% to the Conservatives (with a national trend of 3.1% to the Conservatives). In 2010, this pattern of an over-exaggerated swing continued, with a swing of 5.7% to the Conservatives against a trend of 5.0% (although this was affected by notional changes).
The Conservatives definitely have an uphill task, as Labour had a lot of votes in 2010 taken away by the Liberal Democrats nationally and will doubtless gain those back. The Conservatives could take up to probably 45% of the vote nationally. This could be Labour 36%, Conservatives 45% - therefore just 1% to the Conservatives.
Vote Conservative. Let's try to push this higher than 1%.