Caught staff from this company tresspassing on my property, they did not attempt to knock on the door but instead tried to snoop around the back of the house, well dodgy I think. When challenged the company manager claimed that the staff did knock on the door but did not realise that security camera footage disproved this.
http://www.tvlicenceresistance.info/forum/off-topic/scarf-org-uk-suspect-visit/
Would suggest that if you see this crowd nosing about you treat them with some suspicion.