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

Welcome to 2015! With election year finally upon us, regular readers of this occasionally political website can be confident of an endless stream of wordy (and perhaps even worthy) speculation about the outcome of what is universally agreed to be the most unpredictable General Election in a generation. So I thought it might make a change if in this short piece I focused instead upon a few numbers worth bearing in mind over the coming months.

  • 7.3

This was the extent (in percentage terms) of the Conservative lead over Labour in the national vote in 2010. So remember – a Tory lead anything smaller than this in May implies a net loss of seats to the main opposition party.

There is a tendency to lull ourselves into a false sense of security when looking at opinion polls as if being level pegging with Labour is somehow a competitive performance. In fact, even a 3.5 per cent Conservative lead (not something we have achieved in a single opinion poll since before the Budget of 2012) would imply a swing to Labour of almost two per cent, which repeated on a uniform basis across the UK would make them (just) the largest party in parliament.

  •  25-35

All things being equal (of which more in a moment) this is the range in the number of seats that Labour needs to gain from us in order to become the single biggest party in parliament. Put another way – to achieve this key goal, Labour needs to regain roughly three in every ten of the seats they lost to us in 2010. Whilst we had a mountain to climb last time, in 2015 Labour has to conquer only a hillock.

My ‘25’ assumption is that the gains made from the Liberal Democrats and losses to the SNP or UKIP even themselves out between the two main parties. Clearly, a Labour collapse in Scotland cannot be discounted at this stage, so it is prudent to work on the basis of the SNP gaining 20 seats from Labour (hence the ‘35’ upper threshold figure).

Watch for the variation on our own theme, namely: “Vote SNP, get Cameron”, which Labour hope will get traction. Labour surely start as hot favourites to win back most of the net 13 seats they have lost to Liberal Democrats in 2005 and 2010 (Bristol West, Leeds North-East, Cardiff Central and Cambridge represent the only realistic exceptions), so it is only if the Lib Dems slip well below 30 seats nationally (they won 57 in 2010) that the Conservatives are likely to be the net beneficiaries.

For their part, UKIP will probably secure as much parliamentary representation in previously safe Tory areas as in marginal Tory-held constituencies, in effect depriving Labour of anticipated gains.

We shall hear much before 7 May about the ‘swing back’ from opposition to the governing party that typically occurs in the months before an election. Some of us remember the dizzy double-digit leads that Labour had in mid-term during the 1980s on the road to consecutive defeats. As late as August 2009, the Conservative poll lead was 16 per cent: surely Ed Miliband’s Labour should have been much further ahead if his party is to have any chance of winning?

Instinctively, this seems right – but it is worth reflecting on the relative stability of opinion polling (at least that involving the two largest parties) over the past two years. One reason why there may at most be a very modest “swing back” in the months ahead is that, since 2010, there has been no appreciable shift of voting intention from Conservative to Labour. In short, there is nothing much to swing back.

The two important shifts in voting intention in the past five years have been the upsurge in UKIP support (disproportionately, but by no means exclusively, at Conservative expense) and the immediate transfer of roughly one-in-four Liberal Democrats to Labour on the formation of the coalition.

All the polling evidence suggests that this radical, left-wing element of Liberal Democrat support in 2010 is resolutely determined to vote Labour next time – so no swing back from this quarter, at least. Indeed, this demographic alone has provided Labour with something like a six per cent uplift in its polling figures and, whisper it softly, is the least likely to be persuaded by an aggressive anti-Ed Miliband campaigning line.

Naturally, merely becoming the largest party in Parliament does not necessarily make for a sustainable Government. Indeed, if Labour achieves a narrow lead over the Conservatives in seats this year, it is likely to have won fewer, perhaps significantly fewer, votes than us. Imagine if this constitutional quirk (which occurred in 1951 and February 1974) is compounded by UKIP gaining (as now seems likely) a higher vote share than the Liberal Democrats, whilst winning a fraction of the number of seats (a quite plausible scenario).

Whilst in truth this owes more to Labour’s efficient garnering of votes on lower differential turnouts in their safer seats rather than any intrinsic bias in the electoral system, the public perception of the election being somehow stolen would be strong. This would compound the sense from millions of Britons that our voting system and democratic framework as a whole is not fit for purpose.

  • 1992

Ah, such happy memories for we Conservatives!

Since it became clear that the coalition’s raison d’être of eliminating the structural deficit within this Parliament was not going to be achieved, Conservative strategists have had a keen eye towards framing the May 2015 election as a rerun of that 1992 contest.

Unfinished business on the economy; a profound lack of trust in Labour’s economic credentials; a weak, disrespected Opposition leader with derisorily poor public opinion poll ratings; a widespread sense of disbelief that he has what it takes to become Prime Minister. All the ingredients are there and whilst, as it stands, much of the British public reckon there is little difference between members of the UK’s elite political class, in truth there is probably more to choose economically in the offer between the main parties than at any time in the past 30 years.

Naturally, there are some differences with 1992, too. Then, John Major was able to cast himself as both the continuity and change candidate. Memories of the Winter of Discontent and trade union power meant that Labour was still regarded as extremist by much of Middle England; the relentless press campaign against Neil Kinnock may well be repeated this time out, but newspaper readership has slumped over the past couple of decades – how many voters now pay much attention to what the Sun or Daily Mail have to say?

It is also sobering to recall that despite Kinnock’s famous failure to win the hearts and minds of the British public in 1992, his Labour Party actually made a net gain of 39 seats from us at that election. Superior organisation on the ground then meant that Labour performed disproportionately well in the key battleground marginal seats. Worryingly, Lord Ashcroft’s polling and local election results suggest a similar thing may well be happening at grassroots level today. On a uniform swing, Labour in 1992 would have gained only 19 seats and John Major’s triumph would have yielded a parliamentary majority of 61, rather than 21. History might then have turned out very differently…

  • 9

This is the number of first-term Conservative MPs who have announced that they will not seek re-election in May. A variety of personal reasons, the ever-lower public esteem for politicians and a distaste for parliamentary life all have some part to play in this unprecedented rush for the exit – but it also has electoral implications. The psephological phenomenon known as the double-incumbency effect provides evidence of a two-to-three per cent boost in the average performance of MPs seeking re-election for the first time.

In 1987 and 2001, the elections immediately after landslides which brought exceptionally large new intakes to Parliament, the number of seats lost by the governing party was considerably lower than the average national swing would have supposed.

By rights, we Conservatives should anticipate a similar boost in 2015, especially in view of our inability to implement boundary changes (probably the only silver lining to this failure). All nine of the 2010 retirees who have announced to date are in seats held by Labour between 1997 and 2010, but won back last time. In four of these seats, we defend a majority less than two thousand. In the type of very close-run election that many predict this May, a markedly more difficult battle to retain even a handful of seats might make all the difference between being in Government and losing office.

Whilst each retiring MP has his or her own reasons for stepping down, their decision also suggests that they have each made a hard-nosed assessment of the likelihood of their re-election. It is perhaps instructive that none of the f50 or so from our 2010 intake who inherited Conservative-held seats has (yet) decided to call it a day.

Nonetheless, in this most unpredictable of electoral showdowns one thing is absolutely clear – there is still everything to play for!