The song is referenced in the Guardian article:
As for Dr Who set, it is said
From other reports, Barrowman’s behavior was widely accepted on the Dr Who set. I seem to recall that Catherine Tate said when she first met Barrowman in the makeup trailer, he immediately suggested they swap phone numbers, and the makeup person told her “but he’ll just send you the pictures of his willy” (which he apparently did). She also said when the three of them (plus Tennant) were filming their first scene together, he whipped it out (when he was out of shot), and she was completely freaked out, while David just ignored it. I mean, she was definitely not a novice and could have said something, but if the common attitude was “oh it’s just John being John” I can see how people could not be willing to come forward. In situations like these you’re often made to look as if you’re the problem - “come on, don’t be a spoilsport, have some sense of humour” etc.