Problem with UK Info know is they use the edited electoral roll.
This wasnt so bad when people didn't know they could take there name off the roll, but now they allow you to tick a box and remove your name when the forms are sent out.
This limits how good UK Info is now and you may find older versions better than newer ones, especially if you know the person has lived at the same address for a while.
As for them charging £350 for at best 80% one year old electoral roll, it's laughable!