Last week proved however that political currents are far more complex than simple mathematics allows for. In the key swing seats, of which Lincoln is one, loyalties are more fluid, narrow percentage-based strategies are by nature vulnerable and perceptions count for more than individual policies.

Despite adding a considerable 2,428 votes to our 2010 total on Friday night, we finished behind the Tories again - and by a slightly increased margin: 1,422 votes.

A lot of things went right. Which is probably why our vote increased on 2010 - it certainly didn't everywhere. Our organisation and our ground operation were really good. I was well-supported for more than three years by a genuinely wonderful local team and by passionate and seemingly untiring volunteers - many from Lincoln, many from elsewhere.

We grew our local party and found more and more people who wanted to get involved in our campaign. We contacted voters repeatedly, all year round, for over three years, keeping records of their views and concerns. We delivered Christmas cards and calendars and newsletters and contact cards again and again and again. We overcame the Tories' money with sheer, unrelenting hard work. A great many of our policies resonated well with people we talked to. The national door drop material looked good. I could go on. Ultimately, we persuaded more people to vote Labour and far more people than we expected turned out to put their cross in the Labour box.

But the Tories still got more votes than us. Why? Well in short because the Tories managed to capture some of the 2010 Lib Dem vote, undoubtedly some of our 2010 Labour vote (despite our 2010 vote rising) and stem their UKIP haemorrage, whereas we did not capture as many swing voters and appear not to have been as successful at preventing UKIP slippage. This is, in my view, how.

First, the Tories' negative airwar, based around (1) fear of the uncertainty that would apparently come from Labour being beholden to nationalists north of the border; and (2) a lack of trust in Labour to manage the economy, was very effective.

The upshot of the nationalists' strength would be instability, so the message went - a Labour leader in hock to an ever more strident Sturgeon - and ultimately a greater degree of leftwingery. This exacerbated misgivings about our strength, and most particularly about our economic credibility.

The Tories' use of the more subliminal stuff - billboards, a costly "wrap" around the local paper and local website advertising - appear to have been grimly successful at convincing people that voting Conservative was really the only responsible action it was possible take. This was likely how the Tories were able to attract UKIP-waverers back to their fold.

In the final month of the campaign in particular, I heard from people again and again about the danger posed by the SNP and, by implication, by voting Labour. Sometimes from voters we had recorded as "don't know", but also - on occasion - from prior (and supposedly future) Labour voters. In the case of the latter, I was often asked about the SNP in a way that made it clear that the questioner didn't want the issue to exist and for me to explain the problem away, but I was asked the question nonetheless.

On polling day itself, I knocked on a fair number of people recorded as Labour and who told me they'd voted but wouldn't say for whom. At the time, I was of course at peak paranoia, but I've considered in retrospect whether or not this was in fact the first evidence of the dreaded late swing.

The second reason we failed to win underlies the first: the Tories were only able to exploit people's fears as to the Scottish Nationalists and our handling of the economy because those misgivings existed anyway.

Sturgeon's appearances on television, always bullish and talking-up a deal with Labour, gave credence to the concern that (a) a pact was on the cards and (b) whether there was a pact or not, Sturgeon would be only too keen to wield her influence. Though we ruled out deals repeatedly - and by the end were insisting on minority government - it was too late and, regardless of any truth, seemed to imply at best complication, or at worst to validate Cameron's warnings of "chaos".

As to the economy, it's well-recognised that many still connect Labour with the recession - in part because of the Tories' unrelenting insistence that this was due (backed up by various newspapers), and in part because of our own collective failure to defend this crucial element of our record at a critical time. Although the economic upturn was almost definitely not reaching all - or even most - voters in Lincoln, and despite our rightful highlighting of the numerous weaknesses of the recovery (unbalanced, unfair, unstable etc), the Tories still managed, in my view, to capture from us the territory that goes along with job creation and job security.

As throughout, my evidence is only anecdotal, but I believe that people agreed with us on zero hours contracts and low wages, but enough of those same voters were also concerned that our perceived antipathy towards business may have somehow cost jobs.

Which leads me to the third reason we failed to win, we did not do enough to strengthen our position with swing voters, such that the Tories' predicted onslaught (which was always going to be on economic credibility - the SNP stuff was a fortuitous late boon for Cameron) could have been better sustained.

To some extent, I don't think our failure to attract people to Labour was because of particular policies - we had some excellent "aspirational" policies, such as scrapping stamp duty for homes under £300k and cutting taxes for working people. Rather, the failure was one of tone. We didn't emphasise these policies enough - instead they remained hidden behind scrapping the bedroom tax and raising the minimum wage. Scrapping the bedroom tax was the right policy and we talked about it a lot, yet we only spent 24 hours talking about our stamp duty offer.

In not going out of our way to challenge the caricature of ourselves that the Tories and large sections of the media painted of us, the caricature became reinforced. I think this was fatal amongst the very voters with whom it mattered.

Overall, last week was a disaster for Labour and it's clear that we now have our work cut out, both to reconnect with voters who left us for UKIP and to appeal to those who voted Tory. There are a number of things which would put us on the road to doing so, not least moving the debate on from pre-recession spending, developing convincing answers to questions of Englishness and the new politics north of the border and ensuring that those who work, save and aspire to better things always feel that it's the Labour Party that's on their side.

Everything about last week should have turned me off politics, probably for ever. I worked really, really hard for over three years and saw many volunteers, my friends and young family, make sacrifices to further our cause, and, ultimately, though we performed well locally, we were undone by an unstoppable national current. But rather than losing faith, I've found myself believing even more strongly in the future of the Labour Party this country so desperately needs. I hope all others who also put so much effort into our shared endeavour feel the same.

Lucy Rigby is on Twitter as @lucyrigby. She fought the seat of Lincoln for Labour in the 2015 general election.