What were the biggest canard messages british tabloids ever published?

Question

For example:
In germany the labourorientated tabloid "stern" thought they found the diary of a guy with the initials F.H. and thought it would have been the initals A. H. According to the wellknown checkbook journalism they paid 20 Mio DM for worthless paper.

Answer 1

In 2004 the Daily Mirror printed, in good faith, photographs of British soldiers abusing Iraqis. The photographs were quickly exposed as fakes (a deliberate hoax, in fact), and the editor, Piers Morgan, was forced to leave (in some accounts he was dismissed, and in others he resigned). The hoaxers were soldiers of the Territorial Army, which is surprising, since the publication of the photographs put British soldiers, serving in Iraq, at risk of revenge attacks. One soldier, Private Stuart Mackenzie, was arrested, but proceedings against him were dropped, because the Crown Prosecution Service felt that there was insufficient evidence and an unrealistic prospect of conviction for obtaining property by deception.
http://news.bbc.co.uk/2/hi/uk_news/politics/3716151.stm
http://www.chinadaily.com.cn/english/doc/2004-05/15/content_330996.htm
http://news.bbc.co.uk/2/hi/uk_news/3680327.stm
http://media.guardian.co.uk/site/story/0,14173,1219971,00.html
http://jurist.law.pitt.edu/paperchase/2005/12/british-soldier-will-not-face-charges.php