The “donot delay people” are in Essex. There are so many similar scams that I wonder if they are connected – maybe local “travellers”.
Personally I would not buy or give anything to anyone who only quotes a mobile number – or at the door full stop. There is a good chance they are on the move and dubious.
Local charities deserve the items they are looking for rather than these rag and bone men.
Trading Standards and Local Authorities are unlikely to be interested since the careful wording on the leaflets means they are unliley to be committing an offence (other than not being licensed for collection) any more than the makers of “Utterly Butterly” are in breach of the trades description act. Its all mild deception – irritating rather than criminal.