The Royal Armouries in Leeds has spent an uncomfortable spell in the limelight recently. But its outpost at Fort Nelson in Fareham, Hampshire, has been unaffected.

This armoury holds 300-plus pieces of artillery from all over the world: from pocket-size models such as the trebuchet, (a medieval version of a catapult), to the gargantuan Dardanelles cannon of 1464, which weighs 16 tons and requires a 50lb charge of gunpowder. Little wonder, then, that this is one of the world’s greatest collections of big guns. And all quite at home in one of Lord Palmerstone’s follies.

Students in Years 7-10 at the Admiral Lord Nelson School in Portsmouth are guided by Tony Parry, who explains day-to-day life in the fort, while leading us deep into its inner precincts via a dank corridor hewn out of the rock. We are about to enter “the most dangerous part of the fort”, the powder chamber. It does not bear thinking of what a careless match would have done to the 50 tons of gunpowder once kept here.

The cannon are astonishing. Many are housed in a cavernous exhibition hall and include three of the 26 sections seized from the 160m Iraqi “super gun”, which had a supposed range of 1,000 miles. Other show-stoppers include Britain’s oldest cannon (from 1450) and biggest mortar (1m diameter); and a replica of a gun from the Mary Rose. To test the gun, its latterday engineers fired it at a mock-up of Mary Rose’s hull to see if it worked. It did. The hull was reduced to matchwood.

The barrack rooms house some of the more exotic cannon, not least a Burmese bronze gun immaculately carved with dragons and other images. “Why do you have a gun that’s beautiful?” mused education officer Diane Walker. “Those are the sort of things children should be asking.” One of the most poignant exhibits has a huge dent on the barrel where it took a direct hit from a cannon ball, its gunners certainly killed.

Touching the exhibits is encouraged; but it’s a sobering thought that each and every one, from the delicately intricate to the brazenly crude is still a killing machine. And if you want to know how ear-splitting they sound in action, each day a different gun is fired - on this occasion a howitzer.

Rachel Parkhouse, maths teacher at Admiral Lord Nelson School says:

“There’s so much maths here.” What angle would you fire at? How many men would sleep in the barracks? What about the symmetry of the fort, speed, and the angles between the spokes on gun carriage wheels?

From a maths perspective, she says, Fort Nelson is a gem.

Cynics might think this is a male bastion: not so, says Diane Walker - many girls said they would come again. As for the boys: “Better than maths in the classroom,” says one.

The Royal Armouries Museum of Artillery, Fort Nelson, Down End Road, Fareham, Hants PO17 6AN. Tel: 01329 233734. Open daily April - October, between November and February from Thursday to Sunday. Children free. Book first

* A BATTLE WON

The future of Fort Nelson’s big brother, the Royal Armouries at Leeds, has been the subject of intense speculation. Opened in 1996, it was the focus of the Government’s Private Finance Initiative to attract private sector money into the arts. Royal Armouries International Ltd (RAI), was established with responsibility for the museum building, marketing, front-of-house staff and security. Any profit made by the museum would be divided in a ratio of 8020 between RAI and the Royal Armouries. Losses would be absorbed entirely by RAI.

But the profits failed to materialise. One million visitors a year had been predicted: last year saw fewer than 400,000. This shortfall, together with RAI’s accumulated losses of pound;20m, led to the future of the museum being challenged. But crisis negotiations achieved an 11th-hour rescue package.

Funding has been guaranteed by both the Department of Culture, Media and Sport and RAI’s bankers. The original debt remains RAI’s responsibility and the Royal Armouries resumes responsibility for the museum. Its annual grant, currently pound;4.9m and covering all its sites, will be increased by approximately pound;1m. “The Royal Armouries is safe,” said a spokeswoman for the culture department.

Fort Nelson was never part of the private finance deal and was not under threat.