Out of a registered electorate of 68,517, there were 31,362 valid votes, making a turnout of 45.77%. This was the highest by election turnout since the Romsey by election in May 2000. The Labour Party candidate Iain Wright won the seat with a majority of 2,033, a substantially reduced majority. The Liberal Democrat vote more than doubled, leaving them a close second. The United Kingdom Independence Party held their deposit, and beat the Conservatives into third place. This marked the first time UKIP had come third in a by election. It would be over six years before they ever improved on this position, when they took second place at Barnsley Central in 2011. They would go on to win a by-election for the first time a little over a decade after the Hartlepool contest in Clacton, in October 2014. The Conservative vote in Hartlepool dropped considerably, leaving them in fourth place for the first time in an English by election since Liverpool Walton in 1991. Robert Kilroy-Silk of UKIP initially suggested he might stand but later ruled this out, as did Hartlepool and Middlesbrough mayors Stuart Drummond and Ray Mallon. Preceding by elections had seen the Liberal Democratscome from third place to beat the Conservative Party, and in Brent East and Leicester South take seats from Labour. The seat was safer than Leicester but was vulnerable to swings such as achieved in Brent, or in Birmingham Hodge Hill where the Liberal Democrats narrowly failed to win. In the event, the Liberal Democrats were not quite able to repeat these performances. Their campaign suffered from the choice of a candidate who was not from Hartlepool, while the Labour candidate had been born and brought up in the town. In addition, the Liberal Democrat candidate made reference, on a campaign blog, to having canvassed a street where everyone she met "was either drunk, flanked by an angry dog, or undressed"; this happened despite a Liberal Democrat minder, Ed Fordham, having been appointed by the party's Campaigns Department to proof read Dunn's blog before any posts went up. Fordham removed a reference to some of the people canvassed being Labour supporters, but he thought the rest of the comment was fine. Labour gave wide publicity to this remark and asserted that it was an insult to the people of Hartlepool. Dunn defended her remarks on the Today programme, in a performance that was perceived to be unconvincing, so Labour party vans toured the constituency playing her Today interview on loudspeakers. Hartlepool had no significant ethnic minority vote, which had been present in the other three by-elections. The Liberal Democrats were nevertheless content to claim the large swing to them, and the Conservatives' fourth place established the Liberal Democrats as the main opposition party to Labour in the seat. UKIP did well with a local candidate, and their message of opposition to European Union fishing rules was a popular one in a port town. The Conservatives dropped from second place at the 2001 general election to fourth place, their worst place in an English by-election since 1991. Labour regarded the result as good news for them, as it came at the end of a very long campaign, and with a swing markedly smaller than in other seats over the previous year. Labour also regarded the result – along with that in Hodge Hill – as a vindication of their decision to aggressively attack the Liberal Democrats and essentially ignore the Conservative challenge.
