Harry attended as a representative of England's royal family. There had been some advisers who had warned against it, but Harry was adamant that England had nothing to do with the King's death. If they did not send an envoy it would only appear as if they felt guilty for something.
Harry kept mostly to himself, though he took the time to speak with England's ambassador and other English representatives in the Scottish court. He would have been open to speaking to anyone who approached, however.