The date William Wallace was captured is wrong on the monument
From the Society of William Wallace web site:
David R. Ross, current convenor of the Society of William Wallace, will commemorate the memory of Wallace, by walking from Robroyston near Glasgow, to London, on the 700th anniversary of the actual event.
Wallace was captured on the 3rd of August 1305, and arrived in London on the 22nd of that month, the journey taking 19 days. On the 23rd, he was taken to Westminster Hall, the oldest part of the current Houses of Parliament, where his sham trial took place. He was taken outside and tied to the tails of horses to be dragged the 6 miles through the city to his murder at Smithfield.
Therefore the same dates in 2005 mark the 700th anniversary.
More info here -