Could it be that Labour leader Ed Miliband's demand that all school pupils must study maths until they are 18 has been prompted by new evidence that his own MPs struggle with numbers?

The man in charge of the party's policy review, Jon Cruddas, admitted this weekend that he is "barely numerate". And when the Royal Statistical Society (RSS) recently tested the ability of honourable members to answer a relatively simple mathematical question, only a quarter of Labour MPs got it right.

A total of 97 MPs were asked this probability problem: if you spin a coin twice, what is the probability of getting two heads?*

Among Conservative members, 47% gave the wrong answer, which is disappointing enough. But of the 44 Labour MPs who took part, 77% answered incorrectly.

(*The correct response, of course, is 25%.)

Image copyright MOri/RSS

The survey also asked MPs if they generally felt confident when dealing with numbers -

76% of Tories said they did

72% of Labour MPs surveyed expressed confidence

However, when asked if they thought politicians use official statistics and figures accurately when talking about their policies, only 17% of Conservative respondents agreed, as did 30% of the Labour members who took part.

I wish I had been a fly-on-the-wall when the Ipsos Mori pollsters conducted the survey. The maths question was put to 41 Conservative MPs, 44 Labour MPs, nine LibDems and three from other parties in face-to-face interviews.

Given the confidence in their numeracy expressed at the beginning of the survey, I wonder how the 60% of members who got the answer to the probability question wrong felt by the end.

The research was commissioned by the Getstats committee at the RSS (of which I am a member), part of a 10-year long campaign to improve the way Britain handles numbers.