The fact that his spearmen were using imported pikes with which they'd had little time to become acquainted with whilst their English opponents were using their tried and trusted longbows and bills is also worthy of consideration.
According to "Henry Howard, the poet Earl of Surrey: a life", the pikes ended up dooming their Scottish users for other reasons. Pikesmen were ideal for withstanding cavalry charges, not close-range combat against infantry. See:
http://books.google.com/books?id=7s...EwAzgU#v=onepage&q="Flodden" strategy&f=false
"Scots arrayed in the Almayns [Alemannian, German] manner, that is, with pikes or spears 16 or 18 feet long, Europe's latest weapon technology. ... The long German pikes were superb against horsemen, but hopeless against the English yeomen's short sword or 6-foot bill (a staff ending in a hook-shaped blade) that even penetrated body armour. "
...
"Soon the Scottish spearmen broke their close formations and turned to hand strokes for which their weapons were inadequate. Their horses became unmanageable. ... The English literally hacked the long pikes and then defenseless Scots to death."
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An earlier point of departure might be the sudden death of the English general in the days preceding the battle. Thomas Howard, Earl of Surrey was already 70-years-old at the time and only survived his victory by eleven years. He already had health problems, gout, and "had to be carried in a litter during the Scottish campaign".
Surrey was seen as the definite leader for the troops in the Scottish front, because he had served as the King's lieutenant in the North between 1489 and 1499. He not only had the full trust of Henry VII, but was the man most experienced with dealing with the Scots.
Once he died, the army would be temporarily leaderless until either Henry VIII or regent Catherine of Aragon appointed a replacement. Henry is probably besieging Tournai at this point (the city fell in 23 September), while the heavily pregnant Catherine is heading for Buckingham (she arrived on 14 September). It might take quite a while for a new leader to be appointed.
The most likely replacements are:
*Thomas Howard the Younger (1473-1554). Heir to his father. In 1497, he won a knighthood for his distinguished military service against the Scots. He was appointed Lord High Admiral earlier in 1513. However it is Flodden which cemented his reputation as a military leader. He might have problems convincing others that he is ready to lead.
*Edmund Howard (c. 1478-1539). Marshal of the Horse (Cavalry Commander) of the English forces. Third son of Surrey, second surviving at the time. He lost three horses and was almost killed at Flodden. While arguably a competent soldier, he was never good at playing politics and newer won the favour of Henry VIII. That Henry eventually married one of his daughters came as a surprise.
*Thomas Dacre, 2nd Baron Dacre (1467-1525). Commander of the Border Lancers. Also Lord Warden of the Marches since 1509. He was the one currently responsible for the defense of the Anglo-Scottish border. He distinguished himself at Flodden, cementing his reputation as a soldier.
Squabbling among the three might weaken the English position.