One of the most common critiques of Margaret Thatcher that people have expressed to me in the last few days has been that she oversaw the destruction of British manufacturing.
I've always been a bit suspicious about this narrative - it's undeniable that manufacturing did decline but was this because of her policies or what it something that was happening anyway? So I decided to examine the facts. The figures that follow are all from the excellent House of Commons Library.
In 1970, manufacturing accounted for 31.7% of national economic output. Four years later at the end of the Heath Government it accounted for 28.1%, a decline of 3.6 percentage points or 11.4% over four years. In 1979 at the end of the Wilson/Callaghan Government, it was down to 25.8%, a decline of 2.3 percentage points or 8.2% over five years.
So it was already in decline before Mrs Thatcher came to power.
By 1990, it had declined further to 22.4% of British economic output, a decline of 3.4 percentage points or 13.2% over ten years.
So it continued to decline but at a slightly slower rate than in the 1970s.
In 1997, it was down to 20.2%, a decline of 2.2 percentage points or 9.8% over seven years. And by 2010, it was down to 11.4%, a decline of 8.8 percentage points or 43.6% over 13 years.
So the most rapid decline was under Tony Blair and Gordon Brown; the slowest decline under Margaret Thatcher.
But in politics facts are only part of the story.
(Incidentally, if you're wondering manufacturing has stayed about constant as a share of national output in the first two years of this Government).