This is poor research because it makes links that are not supported by the figures.
They say 7% of parents drink daily, while about a third drink a few times a week. 82% drunk at least once in the previous year, but not regularly. It also says most parents reduce their alcohol intake post kids.
That tells me that the vast majority of drinking parents do so moderately.
It then goes on to say that 'worryingly' 62% of parents don't feel their drinking affects the children. But if most parents drink less than a few a week, that sounds about right to me. What they failed to do, is show how many of the parents that drink excessively, feel this doesn't affect the children. And even then, drinking daily does not equal being an alcoholic. Of the people they surveyed, how many get drunk in front of the kids, or while they are the sole parent in the house? These are the stats they should have researched. What they've got now says nothing.
They then roll out a whole bunch of stats and case studies to show that alcoholism isn't good for children, which nobody would dispute, not even on MC Mumsnet. But these stats prove nothing about how many parents are drinking so much that it has a bad effect, and I really don't see the class link proven very convincingly either.