The moment “316” flashed on to the TV screen at Lib Dem party headquarters I knew election night was going to be bad. If the exit poll was right, there was no way the Conservatives could get so many seats without taking a significant number off us. By the end of the night we had been reduced to just eight seats across the country.

People shy away from articulating the emotional consequences of a loss so comprehensive, preferring catch-alls such as “devastated” and the very British “gutted”. The full range goes something like this: disbelieving, horrified, guilty, embarrassed, angry, vulnerable,resentful.

Nick Clegg's strategist evaluates Lib Dem defeat: 'we got routed by The Fear' Read more

Our campaign was fought on three fronts, and we lost on all of them. In Scotland a tidal wave of nationalism engulfed us, as it did Labour. The origins of the SNP’s rise have little to do with the Liberal Democrats and pre-date the formation of a coalition government in 2010, but shacking up with the Tories and taking co-responsibility for austerity made life even harder than it would otherwise have been. Our campaign in Scotland ended by narrowing its focus into an appeal to Conservative and Labour supporters to vote tactically in Liberal Democrat seats to keep the SNP out. We hoped – and what data we had suggested – we could add Caithness, Sutherland and Easter Ross, Ross Skye and Lochaber, East Dunbartonshire and Edinburgh West to the “safe” seat of Orkney and Shetland. We couldn’t. The SNP turned out its supporters in droves and our squeeze on Tory and Labour voters couldn’t compensate for it.

In Labour-facing seats, many 2010 Liberal Democrats felt we had betrayed them by going into government with the Tories, then by appearing to enjoy their company and finally by breaking our promise on tuition fees. By the end of the campaign we thought we could hold onto Sheffield Hallam, Leeds North West, Bermondsey and Old Southwark, Birmingham Yardley and, at a push, Cardiff Central.

Only the first two made it across the line. Nick Clegg’s repeated apology on tuition fees and our concerted effort to hammer home our achievements in government, including the things we had blocked the Tories from doing, failed to make up the trust deficit.

Should we have run the campaign differently, given what we knew? I don’t think so

In Tory-facing seats we got routed by what I call the Fear. We presumed from the beginning that the Conservatives would try to scare voters with the prospect of a Miliband government that would risk the economy. But in the event the polls and the SNP conspired to ratchet up the Fear to Terror levels, because they showed Labour’s only path to power would be via the SNP.

About four weeks from election day it became clear that The Fear was hurting us. We tried everything we could to counter it: fear of a Tory minority government in hock to its own right wing, Ukip and the DUP; fear of Tory cuts to welfare, schools and other unprotected departments; ruling out participation in any government that relied on SNP support; offering ourselves as the only guarantors of a stable coalition. All of it was trumped by The Fear, and on a scale we didn’t see coming.

Should we have run the campaign differently, given what we knew? I don’t think so. We correctly identified the threats facing us on each front, and did our best to counter them. We made a coherent, liberal case to the voters, offering both a strong economy and a fair society. There are of course improvements that could have been made to the design and execution of the campaign, as there always are, but in retrospect it is difficult to imagine a different campaign producing a significantly better result. Doubtless some will disagree, but consider this: our excellent candidate in Montgomeryshire, Jane Dodds, ran a Roll Royce campaign. Lembit Opik, the man who lost us the seat in 2010, was by all accounts the opposite of an excellent candidate and put in very little effort. He polled 9% more than her.

We have to go further back to understand what happened, to the big judgments that were made in 2010. I have no doubt that going into coalition was the right thing to do for the country, but I can’t help feeling it is the root cause of our current woes. Some argue it was not the fact of going into government that undid us butthe way we went about it. Some will say that our mistake was the rose garden approach, giving liberal and left-leaning supporters the sense of a romance they wanted no part of. While I do think we should have done more to look after the interests of our core supporters in the first half of the parliament, it is wishful thinking to imagine we could have done government differently and convinced supporters deeply averse to our coalition partners.

Red-yellow switchers made the judgment we had sold them out simply by going into coalition with the Conservatives; blue-yellow switchers decided a Conservative government was a better way to secure their economic interests than Labour propped up by the SNP.

My tentative conclusion is that it is probably not possible to succeed electorally in coalition government under first-past-the-post while remaining equidistant from the two big parties. If we can’t win the fight for proportional representation, it may be that we have either to stay in opposition or pick a side. There can be little doubt we would have fared better in this year’s election had we stayed in opposition or, conversely, gone into government and then ruled out any future coalition with Labour – guaranteeing victory in our Conservative-facing seats while sacrificing the rest. But had we stayed in opposition we would have failed the country, and had we abandoned equidistance we would have split the party and compromised its liberal purpose.

There is some comfort in the idea that our defeat this month allows us to return to an idyllic past where we can be ourselves, unencumbered by the ball and chain of compromise with a hated enemy. But there is no such past. Look at the 2005 election, in which we got just 63 seats against an unpopular Labour government and an unpopular Tory opposition. The difference between 63 and eight is less than it seems: neither result enabled us to implement a single policy in government.

There are three options for the party now: remain in opposition unless we can change the electoral system, even if a coalition opportunity presents itself again, allowing us to be whichever version of our liberal selves we like; seek once more to reunite the left by merging or aligning with Labour, thereby creating a path to power for liberal ideas; or rebuild, take the next chance to be in government, and do it differently in the hope of a different outcome.

I appreciate that the immediate task is to rebuild in opposition and win back lost territory by 2020. But since all strategy begins with an objective, I feel compelled to ask: to what end?