LONDON (Reuters) - Britain's King Charles and senior royals will join veterans and crowds to watch a grand military parade and flypast at the start of four days of commemorations to mark the 80th anniversary of "VE Day" - the end of fighting in Europe in World War Two.

The unconditional surrender of Nazi Germany came into force on May 8, 1945, known as Victory in Europe Day, and the British government has planned a series of events to mark the anniversary.

These will begin on Monday when London's famous Big Ben clock strikes midday and extracts from British war leader Winston Churchill's VE Day speech will be read out.

More than 1,300 members of Britain's armed forces will then process through central London from outside parliament to Buckingham Palace, watched by the king, Queen Camilla, Prince William and his wife Kate along with Prime Minister Keir Starmer and veterans of the conflict.

Ukrainian armed forces will also take part to show Britain's support for its war against Russia.

As the procession concludes, there will be a flypast by historic military aircraft and the Royal Air Force's Red Arrows aerobatics display team, watched by the royals from the balcony of Buckingham palace.

The royals will then host about 50 veterans and others who lived through the war for a tea party inside the palace.

“This 80th anniversary is a moment of national unity. A time to celebrate that hard-won peace, honour the memory of those who lost their lives, and remember the sacrifices made by so many to secure our freedom," said Starmer.

In 1945, VE Day was greeted by wild celebrations in London and across Britain.

The late Queen Elizabeth, then a 19-year-old princess, and her younger sister Margaret famously slipped out to join the throng outside Buckingham Palace, believed to be the only time during her 96 years she mingled with the public unrecognised.

"We cheered the king and queen on the balcony and then walked miles through the streets," Elizabeth later recalled.

"I remember lines of unknown people linking arms and walking down Whitehall, all of us just swept along on a tide of happiness and relief ... I think it was one of the most memorable nights of my life."

On Thursday, the actual 80th anniversary, the royal family will attend a service of thanksgiving at London's Westminster Abbey during which Starmer will give a reading.

Government buildings will also observe a two-minute national silence at midday, and the commemorations will conclude with a concert in front of the king and queen.

(Reporting by Michael Holden; editing by Barbara Lewis)