It is estimated that more than 18,000 concrete pillboxes were constructed during World War Two across the UK together with hundreds of miles of defensive ditches and barbed wire. Not since the building of the 'Martello Towers' during Napoleonic times had Britain embarked on such an ambitious programme of home defence.

Today many of these constructions remain, cropping up in the most unlikely of places - with the majority of them to be found sitting forlornly along Britain's coastline. Often crumbling and overgrown, these relics present a vivid picture of Britain at at the beginning of World War Two.

There are many locations where you can find pillboxes and other defences; one such place is located between Brighton and Eastbourne on the A259 Eastbourne Road at Cuckmere Haven.

Now a popular beauty spot and part of the Seven Sisters Country Park, the Cuckmere Haven river valley was a key strategic location for the defence of British shores in World War Two.

Prior to 1940 the area had been extensively surveyed and photographed by Luftwaffe air reconnaissance as a landing area for Hitler’s proposed invasion of England.

If the invasion had gone ahead Cuckmere Haven would have been at the forefront of a German assault. The plan was to sweep up the valley before swinging west to link up with attacking forces landing and parachuting into the Brighton area.

Even when the Battle of Britain had averted this very real threat the area remained heavily fortified with a string of pillboxes sited on either side of the valley. Anti-tank traps and ditches were placed at key access points while the lowland flood plain of the River Cuckmere and the river itself was heavily mined.

During the early part of the war, an extensive network of lights was laid out within the valley. Their purpose was to give German bomber crews the illusion they were over the port of Newhaven, thus protecting the port facilities and drawing them off course for the targets further north.

Later on during the war, an area further inland was developed as an RAF airfield.

A visit to this pleasant area today offers much evidence of its former role and importance. A series of pillboxes, strung along the eastern slope of the valley, can be seen and explored.

Approximately a hundred yards towards the beach a ‘Type 2’ pillbox remains precariously perched on an eroded earth bank.

Commanding a good panorama of the valley this small circular construction, only about eight feet in diameter, boasts walls that are 12 inches thick. It has three loopholes and a small entrance at the rear. Though cramped inside it was designed for four personnel.

Today this round little construction looks innocuous enough but during World War Two it was intended as a very real anti-infantry defence. During wartime it would have been covered in corrugated iron shuttering – the imprint of which can still be seen.

Moving towards the beach on the eastern side of the valley, you will encounter the first of the remains of an interlinked cluster of pillboxes and gun emplacements.

During 1940 the thinking about anti-invasion defences shifted as military commanders moved towards regarding defences such as those at Cuckmere Haven as holding places or ‘redoubts.’

In the event of invasion the Home Guard or infantry manning these pillboxes and emplacements would have been expected, to use the parlance of the time, ‘to give the enemy a bloody nose’. The idea was that by delaying them it would enable mobile infantry to form up further inland, possibly at a pre-arranged defence line or ‘stop line’, for a decisive pitched battle.

Perched on the hillside at the beginnings of the South Downs Way there is what appears to be the concrete base of an anti-aircraft mount followed by a series of pillboxes of various shapes and sizes, most of them remarkably still intact.

A circular Type 2 infantry pillbox, with loopholes to its rear, scans the hillside above a larger concrete construction that features a forward facing embrasure that looks across the valley below. A trench that is now filled in is still clearly discernible and links the two structures.

Less than a hundred yards south, in a small hollow near the valley floor, are the concrete foundations of two more structures together with an intact but small defensive pillbox. Embedded into the hillside, this overgrown concrete bunker is essentially a machine gun nest with a single embrasure cut into its corner that commands a good field of fire across the beach.

Further south towards the sea, two interlinked pillboxes – again of different designs - sit on a grass bank fifty yards behind the remains of anti-tank ditch.

A Type 26 infantry pillbox, made of brick with a sheltered entrance to its rear, boasts several slits for weapons. Further back is a thick-walled concrete pillbox with a single embrasure cut into its corner. This heavy machine gun emplacement offered yet another wide and sweeping angle of fire should the enemy land and approach from the sea.

By venturing a little further up the hillside you can get a good vantage point to view the first line of defence beyond these concrete pillboxes - on the beach. Set back from the top of the shingle bank can be discerned the remains of an anti-tank ditch – cut into the earth to form a degree of protection to the pillboxes above. There is also what appears to be a man-made circular bank.

Descending onto the beach and walking along this ridge, beyond the salt marshes and birds' nesting area, is another anti tank device of the time. Running at a right angle from the eastern bank of the River Cuckmere are the remains of concrete tank traps or ‘dragon’s teeth’. A series of pillars with circular conical tops designed to stop tracked vehicles.

Looking at these forlorn and overgrown concrete pillars now it is hard to gauge how effective they and indeed the other defences at Cuckmere would have been. Yet they remain as potent reminders of what people in Britain were preparing for 65 years ago.

Thankfully never put to the test, today they are overgrown and weathered - happily blending into the landscape and peacefully succumbing to nature and the ravages of time.

For a thorough look at World War Two defences in Britain The Defence of Britain project has, over the last five years, recorded nearly 20,000 twentieth century military sites in the United Kingdom. Visit their website at: www.britarch.ac.uk/projects/dob

For more information on pillbox types visit this fascinating site about pillboxes in Somerset. www.somersetpillboxes.co.uk

www.pillboxesuk.co.uk is another good site about pillboxes across Britain.

Visit the main 24 Hour Museum VE Day index page to find out about Their Past Your Future Events and to explore World War Two-related resources - including trails, features, news and reviews.

If you have memories of Brighton and Hove or East Sussex during wartime and would like to contribute or comment on this trail, try Storymaker our free and easy-to-use web facility that enables members of the public, working with the support of journalists at the 24 Hour Museum, to get their stories online.