Start Bay is wide – and picturesque. But the beach and coastline here closely resemble Utah Beach in Normandy in France, and what was planned for the end of April 1944 were secret rehearsals on Slapton Sands for the D-Day landings.

D-Day. 6th June 1944. That’s 80 years ago this year. Twelve-year-old Harry Beere, the main character in my novel The Kid on Slapton Beach, would be ninety-two years old.

In late November 1943 the Admiralty’s Notice to Leave by 20th December was distributed. Three thousand people were being forced to leave the Devon coast at Christmas 1943, but why?

Imagine packing up your life, not knowing where you will go, or how you will cope? At the time no one knew why, but you obeyed, without question. There was a war on. Businesses had to move. Farmers had to leave their land, remove all livestock, and even dig up planted crops.

Fishermen were forced away to other coasts. Though people did have some help from the Admiralty to move, it was a very difficult time. Leaving home without knowing why is frightening. What will happen to your property? When can you come back? Will you be able to?

Many people had nowhere to go. While some went to family in other parts of the country, others just had to find accommodation where they could, and with limited time to do it. All the while there was no explanation about why they had to leave. Certainly there were American troops flooding into the country. Was it to make way for them? It was the middle of the war. Was an enemy invasion imminent?

The Kid on Slapton Beach, written around the real events of that evacuation, and the subsequent rehearsals for D-Day, has become a best seller in Devon. For young Harry leaving home is very worrying. His father is missing in action somewhere in Italy. His mother can't cope. His little sister is too young to understand. They live in the village of Torcross at the end of the beach, and they are among the three thousand people who are forced to leave the area just before Christmas in 1943.

Helping one of the GIs make friends with locals who are all very apprehensive about what is happening and where they will go, Harry makes a friend himself. He and GI Mike White get to know each other well in the lead up to the exodus.

In the Kingsbridge Museum, the Dartmouth Museum, other local collections, and certainly in the Imperial War Museum, there are many old photographs of GIs surrounded by local children. Of course there were sweets to receive, a real treat in wartime, and new equipment to watch being unloaded, and listening to a different way of speaking - that American drawl, and different attitudes - all new experiences.

There are old family stories about those times, and people, now in their later years, who can remember how their friends and families had to pack their belongings. How hard it must have been to move a whole way of life somewhere else in barely a month. The war demanded so much of them. Rationing of food - and clothing too. And fuel. Keeping the lights off or hidden at night. Double summertime to fit more work into every day. Running to bomb shelters - fast! Women doing the heavy work while their men were away fighting. The emotional strain of not knowing if family members would ever be coming back. Even children had to be brave and resilient.

When Harry, his mother and his little sister leave, his box of his precious possessions is left behind. It contains the only photograph of his father. After an argument with his mother, Harry goes back for that photograph.

It’s the end of April. When Exercise Tiger takes place, Harry's friend the GI Mike White is on Slapton Sands. And Harry - Harry is on that beach too…

Wars have a great many secrets and the D-Day rehearsal on Slapton Sands was one of the darkest. Nearly thirty thousand men took part in the secret full-scale rehearsals for the D-Day landings, and nearly a thousand men died. Everything, everything went wrong! Of course, it was all hushed up. Those who had been there were sworn to secrecy. Had it come out, the American public might have withdrawn their support for the Allies and the D-Day landings were imminent - due just five weeks later.

The secret of that ill-fated rehearsal was kept for decades. Harry would be 92 years old this year and Dartmouth Tourist Office has asked me to make a film about him and his memories, to be shown in libraries, schools and community centres. Harry's story - 80 Years On - is a chance to keep history alive and accessible and to remember the bravery and sacrifice of the ordinary people and the Allied troops involved in this difficult episode of the Second World War. As President Harry Truman said: 'The only thing new in the world is the history you don't know.'

D-Day rehearsals in Devon, 1944 (Dartmouth Museum)

Torcross Village Slapton Sands (Contributed)

American troops landing on Slapton Sands (US Library of Congress)

The Kid on Slapton Beach (Felicity Fair Thompson)