Mark Field is a member of the Intelligence and Security Committee and MP for the Cities of London and Westminster.

Whisper it softly, but for three-quarters of the electorate next May’s election will be anything but unpredictable. As the Westminster Village gets itself with a frenzy of excitement about the outcome, the stark truth is that at least 500 of the UK’s 650 constituencies will absolutely assuredly elect an MP of the same party allegiance as they did in 2010. In all likelihood, a fair few of the remaining 150 battleground seats will do likewise.

So why all the fuss?

Well, unless the opinion polls over recent years have been consistently wrong or they change markedly over the next five months, we appear to be heading for a second consecutive indeterminate overall result. Not bad as a repudiation of the first-past-the-post electoral system, designed to produce ‘strong government’! It will also be the first time this has happened for over a century, and arguably since the Third Reform Act of the 1880s.

Genuinely competitive politics beyond the two main parties has only been with us recently since 1992. As a consequence, tactical voting has become institutionalised. What promises to be new this time is the rise of UKIP as a parliamentary force, and the strong potential in Scotland that the SNP will make a Westminster breakthrough well beyond even its October 1974 performance.

All this suggests that scores of quirky, unanticipated results may be the order of the day on 7 May. Indeed, the disillusionment with conventional party politics stands to be compounded if vote shares and seats won become hopelessly unaligned. Current polling evidence suggests that Labour may end up as the largest single party even in the event of securing some three or four per cent less of the popular vote, – i.e, perhaps more than a million fewer votes, than the Conservatives.

Similarly, incumbency and careful targeting is likely to provide the Liberal Democrats with a substantially larger number of seats than UKIP can realistically expect to win, even if the new insurgent force of British politics secures (as now seems highly likely) third place in the popular vote. None of this will help restore public trust or confidence in a political system or electoral process that worryingly many now feel is broken.

So what of the historical parallels…and can any lessons be drawn?

Ninety-one years ago this month, in December 1923, there was arguably the only instance of a genuine three-way party outcome in modern British politics. As Lewis Baston observed in his excellent article on this site last year, it was this election, coupled with the contest 13 months previously, that marked the point at which the Labour Party overtook the Liberal Party (itself riven by Lloyd George-and Asquith-supporting factions) as principal contender for office to the Conservatives.

What 1923 has in common potentially with next spring’s election is that the number of extraordinary and unanticipated constituency results may prove far higher than normal. That general election was the second of three contests that took place within just two years. The Conservatives remained the largest party (having surprisingly won a comfortable majority in 1922 following the dissolution of the coalition) with 258 seats. Labour won 191 seats and the Liberals 158 – up to a peak from 117 the previous year, only to fall back calamitously to just 40 seats in 1924. The volatility in the third party’s performance was the cause of the sheer unpredictability of so many 1923 constituency battles. It remains the only UK General Election in which three parties secured over 30 per cent of the vote.

Remarkably, the Liberals won a handful of seats (such as Aylesbury, Basingstoke and Blackpool) which had even eluded them 17 years previously in their famous 1906 landslide victory. As well as making hay in the West Country, Manchester and on the Tyne and Tees, a huge swathe of market town English seats fell to the Liberals. Places such as Harborough, Salisbury, Gainsborough, Chichester, Sudbury, Devizes, and Sevenoaks turned Liberal for just one short parliamentary term – returning in 1924 to trusty Conservative hands, where they have remained ever since. Some of the poorest London districts, such as Hackney Central, Camberwell and Islington East were won from the Tories, but by the end of that decade favoured the radical edge of the Labour Party, which has been able to rely upon such seats for the past seven decades.

Perhaps May 2015 will prove a similar election. Some of the seats that unexpectedly change hands may indeed quickly return to type. Others by contrast may take on a fresh allegiance for decades to come. Who can tell? For all of the three mainstream traditional parties the current mood is one of fatalism and some defeatism. All sorts of assumptions have now been washed away.

Until recently (with due respect to our own 40/40 candidates) it seemed pretty difficult to see how Labour might lose seats to the Conservatives. One of the reasons Ed Miliband has faced such a barrage of off-the-record briefing in recent weeks has been the realisation of alarmed Labour MPs that perhaps their dismal 2010 performance of 29 per cent of the vote under Gordon Brown might not, after all, prove to be a low point from which a political bounce back is guaranteed.

Suddenly 20 or so Labour MPs in Scotland alone cannot take for granted their continued parliamentary career. Meanwhile, the rise of UKIP directly threatens a handful of English Labour MPs, whilst others rightly worry that in their particular seat the Conservatives might just come through the middle to win if UKIP disproportionately threatens Labour’s core vote.

These may prove to be very uncharted electoral waters. We have always assumed that in a first past the post system, voters will gravitate towards one of two parties. Traditionally, unless a new party makes a substantial breakthrough within two or three electoral cycles, it risks being squeezed…or so we all thought.

Perhaps the wise money should now be on a headlong rush towards a renewed push for electoral reform. This is especially so if UKIP proves not to be a flash in the pan, both in May and more critically still at by-elections during the next parliament. Anyone out there in the Conservative Party willing to make the case for AV?