Firstly, clothears, my wishes are with you that this is just nothing at all.
Have to say that some of the advice is superb, namely get a professional that is trained to do this to help (FYI Barnardo's has the highest proportion of trained children and family social workers in the country), and also to get medical advice as soon as possible in case there is a need for rapid care or evidence gathering in the unlikely event there is anything to gather. Personally I hold little trust in police investigation first, and would trust a profession that's primary purpose is child welfare or healthcare first.
But, this chap has not been asked what happened. His partner has not been asked what happened. The child is apparently not injured but has been spoken to probably by him about something relating to some pen, and it's sounds just as possible that the girl maight have drawn on something else and been told off for it. I've read, and re-read the original message, and it does not say that he told her that xx wouldn't be her friend any more IF SHE TOLD ANYONE. That piece of damning evidence was introduced into this feed by SOPH28, not clothears. Shortly followed by butterflymcqueen being happy to send him into the baying hordes just on the off chance because it's better to be safe than sorry. And he COULD be innocent. In the UK it's the other way round. He is innocent until proved otherwise.
Please don't think that I'm not concerned, my instincts are to go silly with worry. But, and this is a big but, some of you are suggesting that a man with a daughter of his own be exposed as a paedophile on the off chance that a 3.5 year old child who spoke to her grandma who spoke to her mother who spoke to a thousand people on a website to get advice BEFORE contacting anyone in a situation to deal with it properly. That's almost as awful as what you think might have happened. Those of you that do have partners could test this out by asking them what they think, and how they'd feel if their child was snatched by social services on this sort of evidence.
I hope we are wrong in what we think, I think that should there be a case, then putting names on websites regarding it is particularly ill advised and would harm it. But, remember that a man with a child of his own, that in clothears own words she could believe it of him, is probably guilty of nothing, and the least you could do is ask.