World leaders will gather in France to honour the bravery and sacrifices of thousands of Second World War troops on D-Day 70 years ago.

The culmination of a series of events marking the largest airborne and amphibious assault in military history will be held in Normandy on June 6.

Heads of state from 17 nations, including the Queen, will gather for an international ceremony at Sword Beach, one of the five Allied landing beaches across a 50-mile stretch of Normandy coastline.

It was there that thousands of troops came ashore from the Channel to help turn the tide of war into an eventual victory against Hitler's Germany.

For many veterans, now in their late 80s and 90s, who have made the annual pilgrimage to honour the 156,000 Allied troops, this year's events will be their last to the scene of their exploits.

The Normandy Veterans' Association, whose numbers have fallen to around 600 from some 15,000, will disband in November and their national standard will be laid up at a service in London.

More than 650 UK veterans will journey to France for the commemorations.

Major General Tim Radford, general officer commanding, force troops command, said: ''Every serving regular and reserve member of today's armed forces recognises the bravery, commitment and sacrifice of all Allied personnel who took part in the decisive actions of D-Day and the Normandy campaign.''

William Moody is one of the Commonwealth War Graves Commission's (CWGC) team who has been preparing the cemeteries and memorials ahead of the anniversary.

Mr Moody joined the CWGC in 1968 as a pupil gardener and has more than 46 years' experience maintaining the graves of the fallen across the world.

He said: ''I feel as though I am passing the legacy of remembrance on to future generations, ensuring that we can always come to these remarkable places to reflect on the courage, sacrifice and the real cost in human terms that these men and women made to preserve our freedom.''

Ahead of the arrival in France of thousands of veterans worldwide, a massive security operation will be put in place by the French authorities.

Away from the big events attended by VIPs, including senior Allied representatives, will be a series of smaller gatherings for ex-servicemen to remember their old comrades.

The veterans' heroics in Operation Overlord will be remembered for helping begin the liberation of Europe from the tyranny of Nazi Germany.

The Prince of Wales and Vladimir Putin will be at Sword Beach, in a potentially awkward encounter following Charles' recent remarks about the Russian president.

He reportedly criticised Mr Putin to a woman during a tour in Halifax, Nova Scotia, after she told him how she fled Nazi persecution.

He is said to have responded to Jewish museum volunteer Marianne Ferguson: ''Putin is doing just about the same as Hitler,'' in an apparent parallel with Russia's annexation of Crimea in March.

Some behind-the-scenes diplomatic bridge-building may have to be done if the men are to meet and for their encounter not to detract from the main international event.

Also due to attend Sword Beach will be US president Barack Obama and also German chancellor Angela Merkel, in a sign of the harmony and friendship rebuilt since the horrors of the war.

The day before the main international ceremony, the Queen and the Duke of Edinburgh will travel to France for a three-day state visit, and will be received by French president Francois Hollande.

Following their attendance at Sword Beach, the royal couple will travel back to Paris for a state banquet given in the Queen's honour by president Hollande at the Elysee Palace.

On June 5, Charles and the Duchess of Cornwall will meet veterans, including from the Glider Pilot Regiment, the Parachute Regiment and the Queen's Own Rifles of Canada.

The Duke and Duchess of Cambridge will also play a role by attending events in Arromanches on June 6.

The D-Day operation was described by Prime Minister Winston Churchill as ''undoubtedly the most complicated and difficult that has ever taken place''.

It marked the beginning of an 80-day campaign to liberate Normandy which involved three million troops and cost the lives of 250,000.