most people lived in neighbourhoods and everyone knew one another, it was a community, people did look out for one another, so you would know by way of the local grapevine if there had been a crime committed, particularly domestic related.. pub fights weren't uncommon, but they didn't use a knife, but fists.
2sj has a very good point, that it was unheard of for youths to be involved in serious crime like rape, mostly it was theft, or being under the influence. it wasn't such a thing to be an underage drinker then because generally you did so in the pub, with mum, dad, gran, and grandad, and they would have given you a clout had you behaved badly.....