London - To uncover the scale of compulsive gambling among children, experts used an internationally-recognised test.
It poses nine questions to isolate types of addictive behaviour, including losing control.
A child showing four or more of the different behaviours was considered to be a problem gambler.
Two or three behaviours saw them identified as at risk of problem gambling. A lower score showed they were not in danger.
The nine questions were: In the past 12 months: