See also:-
https://www.gov.uk/child-under-10-breaks-law
and
https://www.gov.uk/if-my-child-gets-in-trouble-with-police
(The expectation for the child to sign the parenting contract could prove a stumbling block, when a 5 & 3 year old are involved).
I have no kids so I'm curious as to what ages kids begin to understand such concepts as property (i.e. other people's), actions and consequences (eg of damaging someone else's property), what money is, what the family doing without 2 grand might entail (eg effect on holidays/Xmas). Forgive me stating the obvious but at below such ages, they should not be allowed outdoors, unsupervised.
Which reminds me, why were the police so blasé about such young children out on their own, unprotected? Isn't that straightforward neglect?