The HPC’s conduct and competence committee will consider allegations that Brennan purchased the blood capsule and gave it to Williams with the intention of it being used to cheat.

Brennan is accused of being complicit in a subsequent cover-up and of fabricating wounds “on a number of occasions other than April 12, 2009”. If found guilty, he could be struck off.

The HPC charge-sheet alleges Brennan’s fitness to practise is impaired as a result of his misconduct.

The two-day hearing in London comes three weeks after Wendy Chapman faced a General Medical Council hearing in Manchester relating to the same incident.

Dr Chapman, who was the Harlequins matchday doctor, admitted cutting Williams’ lip, saying she was under “huge pressure”.

But the disciplinary panel ruled Dr Chapman could return to practising, albeit with a formal warning which will be attached to her registration for five years.

Harlequins’ intention was to engineer a blood replacement in order to get a specialist kicker back on to the field in an attempt to win the game. In the end, Leinster held on to win 6-5.

Harlequins’ then director of rugby Dean Richards was given a three-year ban by a European Rugby Cup appeals panel after Williams changed his evidence.

It emerged during the ERC hearing that Richards had ordered fake blood injuries on four other occasions and orchestrated the Bloodgate cover-up.

The ERC appeal panel gave Brennan a two-year ban from rugby.