One of the early lessons of the pre-election campaign is that statistics aren't the Conservatives' strong point. At the beginning of the month, Chris Grayling was caught out  when he manipulated statistics in order to falsely claim that violent crime had increased hugely over the past decade.
Now, a new attack document from the party, Labour's Two Nations , claims that in the ten most deprived parts of the country, "54 per cent [of teenage girls] are likely to fall pregnant before the age of 18".
In fact, the figures from the Department for Children, Schools and Families  show that, in the areas concerned, 54.32 out of every 1,000 women aged 15-17 fell pregnant, which gives us a figure of 5.4 per cent, not 54 per cent.
This was clearly more cock-up than conspiracy: someone at CCHQ left a decimal point out. But what's more extraordinary is that no one sounded the alarm and pointed out that, regardless of your maths ability, 54 per cent is not a plausible finding. That the figure was repeated three times makes this failure even more remarkable.
Labour can justifiably claim that the error reflects the Tories' dystopian and distorted view of British society.