Which English knight did King Robert the Bruce slay in single combat at the Battle of Bannockburn?

The Battle of Bannockburn took place on 23-24 June 1314. It occurred when King Edward II of England sent an army up to relieve the garrison in Stirling Castle which had been besieged by the Scots. According to Scottish legend, Sir Henry de Bohun saw King Robert the Bruce on his palfrey (a small ambling horse), isolated from the rest of the Scottish army on 23 June, the day before the main battle took place. He took the opportunity to charge at the king, hoping to kill him and end the battle before it had begun. In the ensuing action, King Robert the Bruce commanded his mount to get himself out of the way of the knight’s lance, in a manner which must have also shown him to be a highly skilled horseman, and killed Henry de Bohun by splitting his helmet and head in two with his battle axe.

In another account of the event by an English source, Robert the Bruce chased down Henry de Bohun, who was on his way back to the English ranks.