For all too many British children, the phrase “childhood innocence” is an oxymoron. For my post-war generation, William Brown and his Outlaws would be as close as most of us came to being part of a gang and Richmal Crompton’s eponymous hero’s scraped knees and torn blazer the worst damage anyone suffered.

Fifty years on from the last Just William book, the redoubtable Children’s Commissioner for England has thrown a bucket of cold water over any lingering romance attached to such childhood memories.

Anne Longfield’s report, published yesterday, into childhood violence and vulnerability asserted that some 27,000 under-19s identify themselves as gang members.

More than 300,000 admit to knowing someone who is in a gang. In the past week alone, nine boys have died in English cities, mostly from stab wounds after vicious, coordinated attacks.

NHS officials report that the number of non-lethal assaults of this kind is now running into the thousands. Some of those involved with gangs, according to the Commissioner, have yet to see their tenth birthday. Longfield’s report is based on detailed examination of data from the ONS’s British Crime Survey, backed by a wealth of other research.