The alteration made on May 1, 2000
.........
The second defacement on January 13, 2007
Winston Churchill Statue
London, England
Dates of incidents: 05/01/2000, 01/13/2007

During the anti-capitalist May Day protests in London in 2000, a statue of Winston Churchill in Parliament Square, was daubed in red paint, given a grass mohawk, and the plinth was covered in graffiti. Twenty-five year old Cambridge student and veteran James Matthews admitted to the action and was sentenced to 30 days imprisonment and $250 in fines to the Royal Parks Agency. On January 13, 2007, this same statue was again defaced by red paint poured on its stone plinth.

Sources
http://www.guardian.co.uk/uk/2000/may/08/mayday.world
http://findarticles.com/p/articles/mi_qn4158/is_20000502/ai_n14308462
http://www.independent.co.uk/news/uk/this-britain/may-day-protests-flare-into-violence-718542.html
http://news.bbc.co.uk/2/hi/uk_news/740524.stm
http://news.bbc.co.uk/2/hi/uk_news/england/london/6262489.stm

Photo Sources
left & middle: http://news.bbc.co.uk/2/hi/uk_news/740524.stm
right: http://news.bbc.co.uk/2/hi/uk_news/england/london/6262489.stm