Mandelson comments backfire
It is one thing to be accused of bullying by a journalist with a book to sell who has to rely on anonymous sources.
It is another for someone who runs an anti-bullying helpline to allege that they have been called by staff working directly with the prime minister.
It is no secret that Gordon Brown is not an easy man to deal with. The former cabinet secretary, Lord Turnbull, once accused him of acting with "Stalinist ruthlessness".
Indeed, in recent days and weeks the prime minister has chosen to admit to losing his temper, shouting at people and even to throwing things when frustrated.
However, the attempt of his close political ally Peter Mandelson to justify this behaviour as that of someone who was - in his words - emotional, passionate and demanding, has backfired.
It provoked tonight's claim, which Downing Street will find much harder to dismiss, even though no specific allegation has been made let alone proved.
Some will, no doubt, argue that how prime ministers behave matters much less than what they achieve.
They may point out that were Winston Churchill in Number 10 today, his habit of dictating letters to his secretary from his bath whilst supping champagne, would lead to accusations of sexual harassment and drinking on the job.
Others will argue that bullying - if it took place - is different from other personal behaviour. It is simply unacceptable.