By Paul Adams
Diplomatic correspondent, BBC News, Basra
Basic habits of security are deeply ingrained
In a cavernous single room, with a grubby tiled floor and two rows of imposing columns, 50 British soldiers eat, sleep and go about their duties.
Outside, four vast Mastiff armoured vehicles and a sand-filled blast barrier guard the entry.
The British are here as guests of the Iraqi army - the rest of the old navy base, close to the Shatt al-Arab waterway, is home to 50 Brigade - but the basic habits of security are deeply ingrained.
The British have had their ups and downs here in Basra, but since law and order was restored to the city after fierce fighting between the Iraqi army and local militiamen last spring, life has been less eventful.
The bulk of the British contingent, about 4,000 troops, are out at the city's airport, well out of view of the local population.
But about 200 are still in the city, embedded with Iraqi army units in low-profile "MiTTs" (Military Transition Teams). Their job is to mentor and advise the army as it learns to stand on its own two feet.
Another 650 British soldiers are working in MiTTs outside the city.
The teams are tiny - most of the 50 camped out at the naval base are there for force protection - and they are measuring the progress of their Iraqi counterparts according to a country-wide set of standards - an Operational Readiness Assessment - set by the US-led coalition in Baghdad.
British troops are embedded with Iraqi army units
The British say they are impressed with the mounting confidence of the Basra-based 14th Division, and this week they were pleasantly surprised to see large-scale search operations conducted in the lawless town of Az-Zubeir.
But there is still some way to go, which is hardly surprising for an army defeated, disbanded and then reconstituted from scratch by an invader-turned-ally.
"They've developed some kind of dependency on us," says Maj Adrian Grinonneau, from the Princess of Wales's Royal Regiment.
"We've got to wean them off that in a very short space of time and that's a big task."
But as the date for the departure approaches, there is another problem.
When the last British soldiers leave Iraq, on or before 31 July, many will wonder what their true legacy is.
Knocking an Iraqi army division into shape is no mean achievement, but is it enough?
Gordon Brown, never this war's greatest proponent, set a limited set of goals last summer - complete the training and mentoring of the 14th Division, hand over Basra airport to civilian control, set the environment for successful provincial elections and help to boost investment. Then leave.
The airport is now in Iraqi hands and work with 14th Division is almost complete.
Elections are imminent and the Foreign Office in London says investment worth £9bn is in the pipeline although Basra's filthy streets and open sewers suggest the results may take some time to materialise.
But as the British withdrawal from Iraq begins - some equipment has already been driven out to Kuwait - the Americans are moving in.
They have had small mentoring teams in the city since last August, working with the police, and they will soon take over command of the Basra air station.
To sceptical eyes, it feeds the notion that we are quitting early, leaving the Americans to finish the job.
The British believe the Iraq army are impressive yet still dependent
When I joined an American police mentoring team on patrol through a quiet neighbourhood of Basra Lt Aaron Webb of the 21st Military Police Company said the impression was false, but added: "We're just coming down here to continue on what the British forces have been doing for the last few years."
As the Union Jack disappears and the Stars and Stripes is run up the flagpole, British commanders know the images will appear to tell their own story.
But they insist their own specific tasks are complete and they can leave with honour intact.
The British divisional commander Maj Gen Andy Salmon says his own men tell him it has been worth it.
"They really feel satisfied about being able to look back and say despite the ups and downs and some really difficult periods we're in a really good place."
The British soldiers at Basra's old naval base will be glad to leave their spartan conditions behind and know they will not be around much longer.
Some of them wonder how their work here will be judged.