I remember Rob talking to Ursula about the initial meeting - young girl, what does she know etc.
And didn't he also have a meeting just before he spoke with Alan? Rob mentioned doing psychometric tests - again in an offhand manner.
So he had at least 2 meetings. Presumably, evidence of his bad influence on the boys will have come from the social workers report on Henry.
As for the report, I wonder if it was sent to their lawyers and Helen's passed it on to her, whereas Rob's lawyer hasn't ... 
The report sounded exceptionally frank and damning. I had the view that these things tended to be couched in more ambiguous language. Would this be a typical report in real life? Given Rob's problem personality and his inability to recognise it what, if anything, can the judge do to limit his harm to others he comes into contact with?