Battle of Barnet 1471 - Use of hand guns?

The Daily Mail has highlighted the notion that perhaps hand guns were used in battle as early as 1471 in the battle of Barnet, during the Wars of the Roses. This was the battle that the 'kingmaker', the Earl of Warwick was slain. It has always been said by historians that the earliest hand guns would be used was at the battle of Bosworth Field in 1485 when Richard III was overcome by Henry (Tudor) VII. Where does this place the battle of Flodden in 1513, were hand guns used there?

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