I don't think I've seen that sentence for a while. In these days of data protection would sending out such a list of former winners contravene the act?
I don't think it would breach the act- they would just give broad details- eg Mr S Roe, Belfast. They do list winners of comps in magazines such as TV Choice. Whether the law has changed though regarding this requirement, I don't know.
I think they are still obliged to provide a list of winners on request. But equally they are obliged to protect teh data and would give name and town only.
Of course, it may be that the promoters don't want us to know how many winners there are and don't want us to enquire. It might become obvious, simply from a ball park, common sense, estimate, that your chances of being one are amazingly low.