You might want to read that report again TTT. The charities do not knowingly employ con men.
As I undertsand it, from Radio 4 news broadcasts, Mr Rae completed a survey 24 years ago and did not opt out of having his details passed on to other charities/companies.
Back then it was usual to include a tick box to opt out of having your details shared/sold on, as once a company had your details they could make some money by selling them on to other companies usually for a limited number of mailings.
If you responded to any of those mailings, the company involved could then, legitimately, use your details for further mailings and, if you didn't tick their box to opt out, sell the your details on to someone else.
Most companies who did sell name and address details checked that the people they were selling to were legitimate, and checks were included to make sure that the details were not used more often than had been agreed.
It looks as though someone in one or more charites/companies didn't do proper checks on who they were selling their data to, which is why his details wound up in the hands of con men. And of course once the con men get their hooks into someone they keep the con going until they have bled the victim dry.