Sir Jeremy Greenstock and Colonel Tim Collins reflect on the Iraq war - Guardian

I think at the time there was a case for going in because Saddam was resisting a whole raft of resolutions, building a missile programme that was proven, and the WMD question was unknown. There was a strong case, that Tony Blair made, that better to deal with him then than leave it till later. It was, however, high risk because we hadn't established legitimacy of what were doing.

In the invasion the British did extremely well. It was a high-grade military performance. Post-invasion it was extremely difficult to work within what was an American dysfunctional performance. In the first two years we performed superbly in the south. It was only when Basra politics became so confused and divisive that we found it hard to keep it together. In the end it was the right decision to pull out because Britain had done the job.

It will long be remembered that we were part of a forceful intervention in someone else's territory that a lot of people resented, and many saw as illegitimate. The fact that we did it without full international backing undoubtedly has had an impact on our global image. On the other hand, in the Middle East, we are regarded as understanding the region better than in the US, of understanding local interests better. I think it's not fatal. It's a sticky period but its recoverable.

Colonel Tim Collins, best known for his inspirational speech to his troops on the eve of the Iraq war in 2003

I think the whole scheme ultimately was probably ill-conceived. That was compounded by some poor decisions that were taken shortly after the invasion. There was no understanding of the conditions that we found and no clear strategy and that probably cost something in the order of three years of chaos before things could be restored. It's a tale of two parts. The United States fared poorly at the beginning of the insurgency. Their learning curve was extreme, and I have to say they have come out of it as a thoroughly impressive counter-insurgency force that has achieved tangible results in Iraq.

The tale for the British sadly was the opposite. It was a very different army that went in. The men and women did well as individuals. It exposed the poor level of command and staff - which has been swept away - and a poor performance at strategic level and what the Americans would characterise as an institutional lack of aggression and forward leaning and a capacity for muddled thinking. I think the army is a better army for the experience. It is a better equipped army, it's a better led army. It's an army now with a clear purpose.