On the face of it, the ONS’s loss of nearly half a million people in its mid-year population estimates would seem like a bad news story for the statisticians. But counter-intuitively the omission is a positive sign.

The 2011 Census found that there were 56.1m people in England and Wales, up from the ONS’s extrapolated estimate of 55.6m. Nearly half of the error is a hangover from the previous Census in 2001. At that time the ONS managed to lose a staggering 1m people, most of whom were accounted for in a post-Census review. The remaining 209,000 have been added back into this year’s Census, marking probably the final major adjustment to 2001’s flawed data. Read more