They were already buying bin liners to use at home. When bags were seen as disposable they were often put in public litter bins (where they do not always stay,

They were already buying bin liners to use at home. When bags were seen as disposable they were often put in public litter bins (where they do not always stay, in busy areas with full bins) or simply discarded in the open environment. Anecdotally there seems to be much less of this going on now and the relatively common sight of Tesco carrier bags (other supermarkets are also available, but these seemed to be the worst offender) blowing down the street or caught in trees seems to have largely disappeared from what I have seen since this policy was introduced. There is still litter of course, but the most noticeable litter is now food wrappers rather than plastic bags.