Gavin Barwell held Croydon Central by 165 votes. How did he do it? Labour expected to win here, poured in volunteers, and gained four other ethnically diverse outer London seats from the Conservatives.

Barwell is an expert on campaigning: for 17 years until 2010, when he first won Croydon Central, he worked in various capacities, including Chief Operating Officer and on Lord Ashcroft’s target seat scheme, at Conservative Central Office.

ConHome: “Well congratulations. How did you win?”

Barwell: “I think one of the things that’s been illuminating about this campaign is the Ashcroft poll. It’s given candidates from all parties a lot of data about their seat and what the mood of their seat is. So I had three Ashcroft polls in total.

“The first one was in the autumn, it showed me six points behind, the second one was in March, it showed me four points behind, and the last one was about a week before polling day, showing me four points ahead. But if you go back to the one in the autumn, it gave a very clear route map, strategically, about what to do to win the seat.

“Because what it basically showed was that the voters in Croydon Central preferred David Cameron to Ed Miliband as Prime Minister. It showed that there was a significant incumbency effect for me, because you may know that Ashcroft asked two questions. He asked which party are you thinking of voting for, and then he asks a thinking about the candidates in your seat how do you think you’ll vote.

“And the Labour vote didn’t change between those two, but the Conservative vote went up significantly on the latter question. So it showed there was some personal vote there. It also showed me that the voters in Croydon Central were economically very optimistic about their prospects for the next year. So about two-thirds of people expected their personal economic position to improve over the next year.

“But the downside was that they preferred a Labour government to a Conservative government. That confirmed our pre-existing sense of the seat. So our campaign was very much about trying to identify certain groups of voters who we felt would determine the result. And those groups of voters were basically undecided voters who preferred Cameron to Miliband as Prime Minister, people who were not natural Conservatives but had a good opinion of me as the local MP, and Conservative/UKIP waverers.

“The initial Ashcroft poll had UKIP at 19 per cent, and at that level there is no way I could have held the seat. So we always had a view we had to get that UKIP number down under ten per cent. And in the event we got it down to nine per cent and just about won.

“So these are the three groups of voters. The difficulty then is in fighting a campaign where you are after some quite discrete groups of voters who are quite different to each other. So we designed a number of projects in the campaign which were meant to appeal to these different groups of voters.

“So in terms of the UKIP/Tory waverers, it was crucial to get some of them back, but if the campaign had just focused on them, and if essentially I had just pivotted to the right and talked to those people, I would have lost a number of the crucial voters in the centre that I also needed to win. So the campaign with the UKIP people was very targetted just at them.

“And I suppose there were two key elements to that. The first was to identify them accurately. We were not a 40:40 seat. Central Office had the view initially that we were a safe seat that didn’t need any help.”

ConHome: “Crumbs! That is bizarre. How did they reach that conclusion?”

Barwell: “I think they probably thought I was a former director of campaigns who knew what I was doing, I’d be OK. But nonetheless, we only really got help in the last six weeks of the campaign. So whereas all the 40:40 seats had a long canvassing script that basically asks voters to rank their chances of voting for each party from nought to ten – we looked at that, I could see exactly what they were trying to do with that, because if a voter fills in that script, it gives you very useable data about where they stand.

“But it’s quite time consuming, and quite a lot of voters wouldn’t necessarily fill it in. So we tried to do a sort of half-way house, fudge, whereby we introduced a few local codes that only we would use. We segmented the UKIP vote in half. The canvass code that the party uses for UKIP voters is K, so we used K for somebody who is UKIP and would not vote for us – UKIP and hostile, basically.

“And then we used a separate code, the Z code, which theoretically is for Scottish Nationalist waverers, and we stole that code and used that for Tory/UKIP waverers. So we wanted to know, of these UKIP people, which are the people that are worth going after.

“So that was a key part of the exercise. And in terms of our canvassing, we started the campaign back in June with a training exercise for our canvassers. Because we were sure from the local elections that what had been happening was that people had been going to the door saying ‘Can we count on your support?’ and Tory/UKIP waverers had been saying ‘Yes, I’m normally Conservative’, which the canvasser had taken as an indication they were going to vote Conservative, but actually they were voting UKIP that time.

“So we pressed very hard that if I knock on your door, I have to give you all the options, Labour, Conservative, include UKIP as a prompted option, or not voting, to try to make it as easy as possible to draw out of people that they were UKIP-tempted.”

ConHome: “How many people did you find in that category?”

Barwell: “At various points in the campaign a couple of thousand. It slimmed down as we got nearer because UKIP faded post-Christmas I’d say. And then we had to communicate with them directly.

“The last piece of communication was a letter, we actually used Craig Mackinlay, our candidate in South Thanet, and we got him to write saying ‘I’m a former deputy leader of UKIP, I stood for UKIP in three parliamentary elections, I passionately want to change our relationship with Europe, the reason I’m backing the Conservatives this time is because we’ve finally got a major party promising a referendum. It would be crazy, at this election, to vote UKIP, and stop a candidate who believes in a referendum getting elected.’”

Targetted direct mail was sent, similarly, to voters who preferred Cameron to Miliband, telling them it was a knife-edge race between Labour and Conservative – you must vote Conservative.

Barwell: “The hardest group were the GB [Gavin Barwell] fans if you want to call them that. Certainly some of them were people who’d never voted Conservative before in their life. And when you talked to them on the doorstep you’d have some quite agonised conversations where people would say ‘My father would turn in his grave’.

“They were the most difficult people to win over, but they were also the most important, because you were actually taking a vote out of Labour’s column and adding one to our column. You were taking natural Labour voters across.”

ConHome: “Given that the margin was so narrow, you only needed 83 of those people to switch and you would have lost.”

Barwell said Labour poured activists into Croydon Central, so “we had to recruit lots of new activists”.

ConHome: “How many people did you have out?”

Barwell: “On polling day, we had just over 300 people helping. We tried to vary our literature a lot. We didn’t heavily party brand it because we wanted people to read it. A lot of videos.

“But I think a lot of it is just your work over the previous five years. You know I feel a bit embarrassed being asked to do this [interview], because my majority went down. There are plenty of colleagues who worked hard and have increased their majorities. But I do think in the politics of London it was in relative terms a good result.”

Barwell’s majority in 2010 was 2,969. This time he gained 3,096 more votes, but the Labour vote increased at a faster rate than his, putting him in acute danger.

ConHome: “What’s the ethnic mix?”

Barwell: “It’s a highly diverse constituency: BME population I would guess upwards of 40 per cent. There are actually lots of different communities.”

ConHome: “The Tories have found winning BME votes very, very difficult.”

Barwell: “It is slow progress. I think we’ve made significant progress among the Indian community. Still some progress but less progress elsewhere. In last year’s local elections, we knew we were in trouble, because we lost the council, we lost a ward we’d never lost before, we were behind on the popular vote share. You knew you were in for a fight at that point.”

ConHome: “Are you exhausted now?”

Barwell [without a moment’s hesitation]: “Yeah. It’s not so much a physical exhaustion. It’s a psychological exhaustion. Because it has dominated the last year of my life to the exclusion of virtually everything else. All of the pattern of your waking mind is bent upon this. It’s very difficult to switch off and say for the rest of today I’m not going to think about this again.”

ConHome: “So has that been hard on your family?”

Barwell: “Yeah. Karen is very supportive of what I do, but it is tough on her and the kids.” They have three children aged 12, nine and five.

ConHome: “So what has to be done over the next five years to make sure your majority is even more comfortable?”

Barwell: “In London, the reason we lost Nick and we lost Ange and we lost Mary and we lost Lee” – Nick de Bois, Enfield North; Angie Bray, Ealing Central and Acton; Mary Macleod, Brentford and Isleworth; Lee Scott, Ilford North – “is that London is turning into Paris: the centre is gentrifying and pushing poorer people out. There is a natural demographic challenge there.

“I also think there is a housing issue, the decline in home ownership is more significant in London because of the craziness of the property market.

“The Prime Minister is really passionate about this. He came down to campaign for me about three weeks before polling day, and I got ten or 15 minutes in the green room, just him and I chatting like this, and I don’t think I’m breaching a confidence to say one of the things we talked about was this housing issue, and he was really, really passionate about that – that we’ve got to live in a country where people who work hard have got a chance of getting on the housing ladder. That challenge is biggest in London.”

ConHome: “When did you get interested in politics?”

Barwell: “I got interested when I was very young, my first political memory, I had cancer as a young child, and you had to sort of get helped across picket lines to get treatment, I guess I’d have been seven or eight, and the doctor who treated me left because he got fed up with all the strikes and the whole sort of environment in the NHS. That was an issue I can just remember talking to my parents about and trying to understand what was going on.”

ConHome: “Any other lessons from the campaign for readers of ConHome?”

Barwell: “If I had a message for readers of ConHome, to those who are not actively involved to get actively involved. One of the problems we have, I think, in our party, is that we struggle to match Labour with boots on the ground.

“And therefore if people want a Conservative government they need to actually get actively involved on the ground in campaigning, because seats like mine show that it makes a difference. My majority is the equivalent of four votes in each polling district in my constituency. So the people that helped out on the day made the difference between me being here and not being here.”