Not from the TV show but i have been contacted by a similar company. They check out its not a con but i can't seem to find out what kind of ball park figure they go after. is there a minimum amount in someones estate before they will go after it?
There was an article about this in the media last year. They go after anything over £500 and take approx 40% fee, ... I don't kow if these figures are true though, I'm only going by the story in the paper last year. Ask them beforehand. They're obliged to be up front with you IF IF IF they're genuine.
My view is that you refuse to sign until they reduce the percentage. They'll probably come in at around 40% but know that others will also be chasing you. They also know you could find out by yourself so nail them down to the minimum percentage you can.
They cant actually determine precisely what the estate is valued at since the BV department will not give out these details until someone is confirmed as a bona fide heir. The heir hunters work on the basis of searching the individual and seeing if they owned their house. If the deceased owned their own house (easy to check with the Land Registry) they will go for it. If they lived in a council property it is far less likely - although they will still take a punt on an easy case.
You could probably find out who it is by yourself with a look at the Bona Vacantia list and a brief look at your family tree. It wont be difficult.