Was the downfall of Richard III caused by a Strawberry?

Richard III's actions in the summer of 1483, when he unexpectedly put aside his twelve-year-old nephew and became King of England, are considered to be out of character. Could a food allergy have triggered the series of events that lead to the fall of the House of York?

Here's my piece in the New Statesman:

http://www.newstatesman.com/ideas/2013/08/was-downfall-richard-iii-caused-strawberry