Studies of recent British general elections have shown that the amount spent by candidates on their local campaigns was closely linked to the outcome in their constituencies; the more they spent the better their performance. Such research was hampered, however, by the short period for which spending returns were available; campaigning begins long before then. The 2010 election was the first for which candidate spending data were available for a longer period, when candidates could spend about two-and-a-half times as much as the legal limit for the 'short campaign' immediately preceding election day. This first detailed analysis of those data addresses variations in the amount spent across constituencies and their impact, focusing on whether spending on the two campaign periods had separate and independent impacts. Intensive local campaigning - as measured by the amount spent - during the long campaign provided a vote-winning foundation, on which the short campaign then built, especially for the two parties that raised the least money to spend in the months preceding the official campaign.