General election: Do Conservatives claims about Labour's spending plans add up?

Conservatives have taken a leaf out of the Vote Leave handbook by putting a Very Big But Questionable Figure (VBBQF) at the heart of their campaign efforts over the past few days.

For Vote Leave, of course the VBBQF was £350 million - the supposed amount handed over by the UK to the EU each week - which was plastered over Boris Johnson’s battlebus and mentioned by campaigners on every possible opportunity despite being ruled “misleading” by the official statistics watchdog.

For Tories in this election, the figure is £1.2 trillion - the additional spending which they claim Labour is committed to over the next five years, despite the fact that Jeremy Corbyn’s party has not yet agreed its manifesto or set out its plans.

Although this VBBQF was rejected as “ludicrous” by Labour and questioned by many observers after being dropped in sympathetic newspapers on Sunday, Conservatives have followed up today with a claim that the supposed extra spending would cost the average worker a month’s wages each year in higher taxes.

So how was the figure calculated, how reliable is it and what is the tactical thinking behind its use?

1. How is the figure calculated?

   Conservatives say that they have taken the costs of measures included in Labour’s 2017 manifesto - calculated at £600 million over five years - and added another £590 million to cover promises made over the following years.

   Having reached the total of £1.2 trillion, they then subtracted £546 billion relating to capital expenditure which could be funded by borrowing under Labour’s fiscal rules. Of the remaining £651 billion, some £277 billion is covered by tax increases already announced, leaving a £374 billion “black hole”, according to the Tory figures.

   Dividing this figure by the 19.1 million families in the UK produces a figure of about £19,600 over five years - the equivalent of around £3,900 a year or £75 a week per household, which the Tories estimate at £2,400 for each taxpayer.

2. How reliable is it?

   At the point of their release, there was no way of knowing. Absent a manifesto with agreed policies, it is clear that anyone trying to cost Labour’s plans for the coming five years would be relying on informed guesswork.

   Several elements of the Tory figure are drawn from motions backed at Labour’s annual conference which may or may not feature in the manifesto. These include £35 billion for abolishing private schools, which Labour has already said is not its policy, and £10 billion a year to build socially-rented homes, which has not yet been formally adopted as a pledge. The £17 billion-a-year estimated cost of moving to a four-day week has been included for each year of the five-year parliament, while Labour says the change would be phased in over a decade.

   The Conservative figure includes £38 billion for public pay increases, based on a statement Mr Corbyn gave in 2018 backing union calls for a 5 per cent pay rise, which would not necessarily apply to the coming five years. The Tory figure assumes that Labour will carry over every commitment from its 2017 manifesto, but its estimate for the cost of this is more than double the £48.6 billion annual bill which Mr Corbyn’s party announced at the time.

   The figure includes £196 billion for nationalisations, drawing on a CBI estimate which has been challenged after it included the price of rail rolling stock which Labour says it would not buy.

3. What is the tactical thinking?

   Clearly, any claim that a rival party is planning massive overspending requiring tax hikes to fund them is political golddust in an election period. Translating the big overall figure into the amount it would mean for individual incomes is a tried and trusted practice.

   But it has previously been assumed that any figures that are not watertight risk rebounding on those using them by raising questions about their trustworthiness.

   However, the experience of the 2016 EU referendum has raised questions about this assumption.

   Vote Leave campaign chief Dominic Cummings - now at 10 Downing Street - has himself spelt out how a questionable figure can have more clout in an election battle than one which is uncontested.

   The theory is that if a party puts out figures which are open to question, they will attract rebuttals from opponents and scrutiny from the media in a way which totally reliable numbers would not.

   The more the figure is debated in the newspapers and on TV, the more that activists build it up or tear it down on social media, and the more analysis it receives in fact-checking services like this one, the more likely it is that voters will notice it and remember it. And crucially, the question being asked will be “Are they really going to spend that much?” rather than “What are we going to get for this money?”

   Despite the £350 million figure being denounced as misleading, and despite the fact that there has never been a week in which the UK handed that much money over, it is probably the only number that most people remember from the 2016 campaign.

   Cummings himself said in a blogpost that Vote Leave was aware that roughly half of the £350 million was returned to the UK, but used the figure “to provoke people into argument” adding: “This worked much better than I thought it would.”

   He credited the £350m figure as one of the key factors that won the referendum for Leave. The big question now is whether £1.2trn will gain the same traction and win the election for Conservatives.