A memorial will be held in the UK and the US on Friday to mark 30 years since the worst terror atrocity in Britain.

It was on December 21st 1988 that a Pan Am jet travelling between London and New York exploded over the Scottish town of Lockerbie.

All 259 passengers and crew on board were killed.

Eleven people were also killed on the ground when the wreckage fell.

A service of commemoration and a wreath laying will take place to mark the anniversary and remember the victims.

Bereaved relatives will be among those gathered in the town's memorial garden.

This December 1988 photo shows seats among the wreckage from Pan Am flight 103 in Lockerbie | Image: John Giles/PA Wire/PA Images

Colin Gordon lost his older sister Olive on board flight 103.

His sister was 25 at the time and was travelling to New York on holiday to visit friends.

In a tragic twist of fate, she had actually been due to travel on an earlier flight and only boarded the doomed aircraft because she had been delayed.

Colin was working in a hotel in Jamaica when he heard the news.

"I was handed this note. I opened it and it had this really bizarre message. It said 'come quickly, bring passport - death!'"

He said that when he realised what the note meant he felt "like someone had hit me with a sledgehammer".

But he said that in the following years the hardest part to deal with was the effect on his and Olivia's mother.

"I think that was the toughest thing," he said. "Watching my mother go through what any parent would dread - burying their child. That was the toughest thing."

The Lockerbie disaster remains Britain's biggest terrorist atrocity.

Undated file handout photo issued of Lockerbie bomber Abdelbaset al-Megrahi | Image: Crown Office/PA Wire/PA Images

A bomb exploded in the luggage hold of Pan Am flight 103 at 7.03pm as it flew at 31,000 feet en route to New York's JFK airport from London Heathrow.

The victims came from 21 countries - most were from the United States.

Only one man has ever been convicted of the bombing, Libyan national Abdel Basset ali-Mohmed al-Megrahi who died in 2012.