Royal commissioner Dyson Heydon's "overlooking" of the Liberal Party connection to the event at which he agreed to speak -- a connection made clear to him just under a year earlier -- isn't the first time the trade union royal commission has been troubled by someone's faulty memory.

On the day of Julia Gillard's evidence last September, the case against her imploded when former union official Rob Elliot retracted claims he had made about Julia Gillard's involvement in the establishment of a union election organisation, saying "it is a great distress to me that now having formed the view it is a false memory I'm describing here, that it  is the subject of consideration by a Royal Commission."