GORDON BROWN yesterday hailed the British military’s involvement in Iraq a “success story”.

Speaking to troops during a surprise visit to the country, the Prime Minister revealed for the first time the official schedule for withdrawing the final 4,100 UK forces from Iraq.

He said military operations would be finished no later than May 31. Virtually all British forces will leave by the end of July.

Looking back over nearly six years since the US-led invasion in 2003, Mr Brown urged: “I hope that you can see the difference that you have made over that period of time, this is a success story thanks to you.

“You are making a difference in the great spirit of our British armed forces.”

The announcement came on a whistlestop visit by Mr Brown, which included talks with Iraqi Prime Minister Nouri Maliki.

Further details of withdrawals will be spelt out to the House of Commons when the premier makes a statement to MPs today.

Before leaving Iraq last night just over ten hours after arriving in great secrecy, he gave a pre-Christmas thank you message to the troops at their Basra airport base.

Praising their courage and patriotism, he said: “We set ourselves tasks, and thanks to you we have achieved them.

“So I was able to say to Prime Minister Maliki today that we will be able to complete our mission before the end of May next year.”

Earlier, Mr Brown laid a wreath at a memorial for UK service personnel killed in Iraq – now 178 in total.

“They will not be forgotten,”

he said. “I am grateful to all those who have served.”

The future of the memorial, situated outside Basra airport, has been one of the issues Mr Brown has been considering during the visit.

It has emerged that it is likely to be moved to the UK as the last British troops leave.

As well as the usual prime ministerial stops in Baghdad and Basra, the Prime Minister took a helicopter ride to the southern port of Umm Qasr.

Mr Brown was joined for the trip by the Chief of the Defence Staff, Air Chief Marshal Sir Jock Stirrup.

He played down the prospect that troops would simply be transferred to Afghanistan, and dismissed any suggestion that US president- elect Barack Obama would ask Britain to take up a greater share of the burden.

Sir Jock said: “We cannot just have a one-to-one transfer from Iraq to Afghanistan.

“The net result must be a reduction in our operational tempo because the forces have been overstretched for too long.”

But he also said that military chiefs had to look at the “requirement on the ground”.