The 'school bobby' still exists but under a different name. (It was 'educational welfare officer' when I was teaching but they've probably changed the name again by now).
In many areas, education staff carry out patrols of areas such as shopping centres, to try to identify truants. (They always work alongside the police so that there can be no worries about 'adults approaching children'). Local education authorities are also getting much tougher about taking court action against the parents of truanting youngsters.
However, there can only be limited success where the parents don't support schools. I remember the situation where, in the school I taught at, the head of year phoned the mother of an absent 13-year-old to ask why he wasn't at school. The reply he got was very abrupt. The parent made it extremely clear that she detested this 'victimization'. She stated that her son was unwell and unable to get out of bed. She took strong exception that my colleague might even be suggesting anything to the contrary.
Later the same morning, that mother took a short cut to the shops, through the school grounds. She was accompanied by her 'sick' son and the couple stopped right outside the head of year's classroom, so that she could light her son's cigarette for him!
Chris