Media playback is unsupported on your device Media caption Michelle Fleury reports from St Lucia: ''What was meant to be a great adventure, has turned into a nightmare''

A British man has been murdered on the Caribbean island of St Lucia as he tried to defend his wife from attackers.

Roger Pratt, 62, was killed on board the couple's yacht in the town of Vieux Fort on Friday night, police said.

His wife, Margaret, was treated for injuries sustained in the attack, which took place while the Warwickshire couple were on a round-the-world trip.

Police said three people were in custody, but no arrests had been made.

Mrs Pratt had been released from hospital and was helping detectives investigating the robbery, they said.

The UK Foreign Office said it was aware of the death of a British national on the island and was providing consular assistance to the family.

The West Indies is one of the most popular destinations for sailors. St Lucia is the first stop for many boats coming across the Atlantic just like Roger and Margaret Pratt had done. Most people tend to stay on the more popular and touristy north coast of the island but the couple headed south towards Soufriere and the volcanic World Heritage Site, the Pitons. According to posts on social media they were delayed by customs there so they continued down to Vieux Fort. It's a stop off before people cruise the chain of small islands in the eastern Caribbean that was part of their round the world adventure. There are fewer yachts in the area and most boats don't go into the marina but sit at anchor in the bay, this is where Mr and Mrs Pratt were attacked. Thefts from boats has been a problem in St Lucia in the past, but it's uncommon for criminals to target them whilst owners are on board.

The cause of Mr Pratt's death has not been established, but police said there was no evidence he had been shot. A post-mortem examination is due to take place on Monday.

A police spokesman said: "Nobody has been arrested yet but there are some guys in custody. The investigators are very busy looking at what happened."

'Found floating'

He said that officers heard that three armed men had boarded the boat, named the Magnetic Attraction, and attacked the couple before fleeing.

"Margaret went in search of her husband and found him floating in the nearby waters.

"Roger was retrieved and transported to St Jude Hospital via ambulance along with his wife.

"He was pronounced dead on arrival while Margaret was treated and discharged."

The couple had been on their voyage since June, when they left Lowestoft, Suffolk, and headed for the Algarve before navigating their way to the Caribbean.

They had been celebrating Mrs Pratt's birthday when the attack took place.

While on their trip, the couple kept a blog.

Writing hours before the attack, Mrs Pratt said they had planned to leave the island some time before, but immigration checks had been delayed.

Image copyright AP Image caption The couple had been celebrating Mrs Pratt's birthday on the island of St Lucia

On 10 January Mrs Pratt wrote about her birthday.

"Yesterday was a very special day. I had a blissful time!"

Later she wrote that the couple had enjoyed an evening with their friends.

"The evening went with a swing, aided by a local rum punch with fruit juice that definitely packed a punch!

"Altogether a delightful and memorable day. Happiness is..."

Mrs Pratt has worked as a financial adviser for NHS Northwest and was the chief executive of St Mary's Hospital and Isle of Wight PCT, according to her LinkedIn profile.

Writing in her blog on 13 November, Mrs Pratt said they were planning to attend seminars at a yacht club in Lanzarote on dealing with emergencies at sea.

Her husband "went to a session on piracy and found it interesting in terms of practical tips", she wrote.

Meanwhile, St Lucian tourism minister Lorne Theophilus extended "sincerest condolences" to Mr Pratt's family.

Media playback is unsupported on your device Media caption Neighbour Lavinia O'Shaughnessy: "They were really keen on the water."

"To his wife, who also sustained injuries as a result of the attack on the Vieux Fort coast, we extend our deepest sympathies," he said.

"This is an active investigation and law enforcement is leading the charge in an attempt to bring the perpetrator or perpetrators to justice speedily.

"Law enforcement officials have briefed myself and other senior tourism officials on aspects of the case although I am not at liberty to share some of those details with you at this time."

Speaking from her home in Moreton Paddox, near Stratford-on-Avon, Warwickshire, neighbour Lavinia O'Shaughnessy said she was shocked at the news.

"They were very sociable, Margaret is a very jovial person.

"When we moved here they were very kind to us, they are a nice couple.

"I'm very sad, they were some of the nicest people you'd like to meet."

Susan Barraclough added: "It's dreadful news for anybody, but it's even worse if you know them. Just dreadful."

Rev John Parker, vicar of the Midfosse parishes which includes Moreton Paddox, said prayers for the couple had been said at Sunday services.

"They set off on the experience of a lifetime only for them to have been set upon, it seems, by robbers in a crime that appears to have gone horribly wrong.

"Our hopes and prayers are with the family and particularly Margaret, and we wish her a speedy recovery."