Not sure if the lad - who looked no more than 10 years old - was meant to wash them, fold them and send them back, but the gesture was par for the course for Williams.
Twenty nations contested the 2015 Rugby World Cup and each squad would have comprised 30-plus players, so let's say more than 600 players in England for the biggest event of their sporting lives.
I do not believe a single one of those players would have done what Sonny Bill did - the unthinkable.
Having helped the All Blacks see off Australia in the final, he then gave away his World Cup winners medal to a young English lad who had run toward the pitch in all the excitement and been bowled over by a security guard.
Generosity verging on madness.
Who knows what next from SBW, but he is in danger of becoming a poster boy for his Islamic faith, role-modelling behaviour that punctures the often-negative archetypal view of the Muslim world.