Adair

It was in the spring of the year 1894 that all London was interested, and the fashionable world dismayed, by the murder of the Honourable Ronald Adair under most unusual and inexplicable circumstances.

I believe that on the day of the murder Adair had discovered that Moran was cheating. Very likely he had spoken to him privately, and had threatened to expose him unless he voluntarily resigned his membership of the club, and promised not to play cards again.