There is a constant battle going on at Brean Down. But it's not in the empty Victorian fortress or the windswept World War II gun emplacements.

The war is taking place beneath the feet of the hundreds of tourists who climb along the ridge of the Down each day.

It is a real battle to maintain the rich limestone grassland on the headland.

The verdant promontory, which extends for 1.5 miles into the Bristol Channel between Weston-super-Mare and Burnham-on-Sea is surprisingly delicate.

Every day the bracken reaches out its thousands of grasping new shoots, keen to occupy the dramatic strip of land, and each day it's fought back by the wardens and volunteers from the National Trust, which has managed Brean Down since the 1950s.

The man tasked with stopping the treacherous advance of the bracken is Mark Courtiour, the National Trust's countryside manager for Somerset.

He explains: "If it's allowed to take over, the whole of the Down will become scrubland, and that would be a disaster, because limestone grassland is such a rare terrain, and it hosts lots of unusual species of plants and insects.

"For example, the White Rock rose is common here, but this is one of just a handful of places in the country where the rose can be found.

"We also have Chalk Hill Blue butterflies, which thrive in limestone grassland. They're two very good reasons why we need to keep the bracken back."

But with just three wardens and around 20 core volunteers to help him, Mark certainly has his work cut out.

"That's why I'd be really keen to hear from people who would be able to volunteer some of their time to help cut the bracken back," he says, as he looks up at the steep-sided hill.

"The National Trust has always thrived thanks to the hard work of its thousands of volunteer helpers, and we always need more pairs of hands to help us to maintain this rare landscape for the nation."

Few people know Brean Down as well as Mark, who has been a warden in the area since the early 1990s.

"We do have help from other creatures too," he says, as we head up the steep 152ft-high slope. "In the summer months we graze a herd of hardy White Park cattle on here, and there is a resident herd of goats here all year round. They all help to keep the scrub down.

"Our goats have been here since the 1970s, when the original group of nine animals were introduced to the area. They almost live wild on the Down, and their numbers have stabilised at around 50, which is about right for the 160 acres."

Thousands of visitors take advantage of the dramatic coastal scenery each year, which is freely accessible to all as a National Trust admission-free site.

"It's a funny thing," Mark says. "The National Trust was set up in 1895 as an organisation to maintain the countryside and places of natural beauty for the nation, and it was only later on that the Trust started to be left the big houses and country estates in legacies in the 1940s.

"But these days when you say National Trust, everyone thinks of big old houses. In fact, the countryside element is still a big part of the Trust's work. We work continually to preserve some of the country's most iconic landscapes."

Few are as iconic as Brean Down. As we reach the tip of the Down, with its robust Victorian fortress, the angry brown waves of the Bristol Channel crash against the cliff below.

"It's a wonderful spot," Mark says. "The fortress was built in the 1860s, at a time when the French were threatening to invade the country.

"They never got this far, but much of the fort was destroyed by one of the garrison's own soldiers, who committed suicide here by firing his rifle into the explosives arsenal. It caused a tremendous explosion, which destroyed one whole side of the building."

The fortress is now an historical mishmash, dotted with the concrete gun emplacements built here during World War II for similar defensive purposes.

"Later in the war the military used Brean Down as a site for testing experimental weapons, including a so-called expendable noise maker, which was designed to interfere with submarines' sonar systems.

"They also carried out some of the early experiments here with Barnes Wallis's famous bouncing bomb."

A pair of metal tracks still run off the end of Brean Down, from where the wartime boffins could have launched the bomb into the sea in order to perfect that tricky bounce.

The war also left its mark on Brean Down in an even more literal way.

"The RAF built a concrete arrow on the top of the Down," Mark explains. "The arrow was there to point our trainee bomber pilots in the right direction, so they would drop their payload into the Bristol Channel rather than on to Weston-Super-Mare," he laughs.

Archaeologists have discovered that the headland has been used as a defensive base since at least the Bronze Age, and they have even discovered the remains of a Romano-British temple on the top of the hill.

"It really is a wonderful place, rich in history and natural beauty," Mark says. "It's the sort of place that really sums up the work of the National Trust perfectly."