Residents have been warned to be vigilant about so-called Nottingham Knockers.

Nottingham Knockers is a general term relating to unlicensed doorstep sellers who will offer a selection of household products for sale. Many claim to be ex-convicts on some kind of rehabilitation scheme.

They are not, however, involved in any official recognised rehabilitation programme and don’t carry pedlar’s certificates which are legally required to sell door-to-door.

Purbeck police say they're currently operating in Swanage and Wool and officers have warned the the public to be vigilant.