Nglish Criminal law Problem question Discuss the criminal liability, if any, of Bruiser for the murder of Dot

The facts of the case are that Bruiser MacFist a retired heavyweight boxer and chronic alcoholic, was out celebrating in a local club with his partner, Patsy a former prostitute, now a beautician with whom he shares residence in a respectable neighbourhood.
In the bar of the club, they start a conversation with Alf and Dot, who they have not seen before in the club. To their surprise, Alf says to Patsy in a very loud voice overheard by everyone in the bar,  Are you still on the game, darling? Didn t I see you touting in the High Street? . Bruiser reacts angrily, shouting  I ll soon shut you up! , and swings his fist at Alf.
At that precise moment, Dot moves towards Alf for protection as she sees a fight developing. Bruiser s fist, heavy with rings, hits Dot on the side of her head. Dot falls to the floor and dies of a heart attack: she had been in poor health due to a weak heart for some time.