The "appalling" errors that contributed to Britain's failure in Iraq are disclosed in the most detailed and damning set of leaks to emerge on the conflict.

On the eve of the Chilcot inquiry into Britain's involvement in the 2003 invasion and its aftermath, The Sunday Telegraph has obtained hundreds of pages of secret Government reports on "lessons learnt" which shed new light on "significant shortcomings" at all levels.

They include full transcripts of extraordinarily frank classified interviews in which British Army commanders vent their frustration and anger with ministers and Whitehall officials.