Would you stop a litter bug or avoid getting involved?

If you saw someone drop rubbish in the street, would you accost them or avoid getting involved?

BBC Radio 4 newsreader Alice Arnold is being hailed as a "litter crusader" for standing up to a pair of litter louts who threw an empty bottle out of their car window by simply throwing it back in.

The environment secretary Caroline Spelman says we should all be ready to challenge litter bugs, but are we?

John Maguire reports.