Although a little larger than king size, an unusual bed stored in Britain's Palace of Westminster with a remarkable history could see its first royal sleepover ahead of Charles III's coronation in May.

The regal crib, which has its origins in a thousand-year-old tradition observed up to the time of Henry VIII in the 16th century, was lost for decades but is ready for service after a remarkable journey.

On the night before coronation, the sovereign traditionally spent the night at the Palace of Westminster, then the Royal Palace.

After falling out of favour, the tradition was revived two centuries ago for the coronation of George IV in 1821.

But that bed was destroyed in the fire that ravaged Parliament in 1834.

So another one, finished in 1858, was made but has "actually never been used the night before the coronation", parliamentary historian Mark Collins told AFP.

Discovery in mill

It was not ready for Queen Victoria's coronation in 1838 and subsequent monarchs chose not to spend the night at Westminster.

The bed was dismantled and stored away during World War II, forgotten as the Victorian era fell out of fashion.

Its whereabouts were unknown at the time of Elizabeth II's coronation in 1953 and it was not until the late 1970s that a V&A Museum expert, Clive Wainwright, launched an appeal to try to find the bed.

His efforts proved successful, with a family coming forward to reveal it was located at a woollen mill in Wales.

It had been bought at an auction for £100 ($119) in the 1960s by the parents of Richard Martin, now 70.

"They knew it was a special item, they knew that it was something important, but they didn't know where it had come from at all," said historian Collins.

And for about 20 years, the bed had a very busy life. One of the family's children, Benedict, was even born there in 1965.

'Night-time throne'

The fantastical piece stirred the imagination of a young Richard Martin on his way to the land of nod.

"When I was a child... we thought that whoever lived in the bed, who slept in the bed, would put their cigarette" in little holes carved in the wood, while reading or drinking tea, he told AFP.

"Nobody else had a bed like that", he said, calling it "a night-time throne".

The bed was bought back from the family and then restored.

The original royal red and purple hangings, adorned with the rose for England, the thistle for Scotland and the clover for Ireland, had long disappeared and were recreated in 1984.

The public can now see the piece following Speaker Lindsay Hoyle's decision to open the rooms up for tours, but it will be hidden from view during the King's coronation weekend, starting May 5.

The "State Bed" lives a stone's throw from Big Ben in a dedicated room in parliament's Speaker's quarters, with windows overlooking Westminster Bridge and the London Eye.

The upper part of the bed, which has a walnut frame with gilding and royal symbols, is over three metres (about 10 feet) high.

The question now remains whether Charles will captain its maiden royal voyage.

Ms Collins said it will be ready for action, whatever the decision.

"I don't think it'd be too long before we actually find out whether it'll be used again.

"The bed the bed is definitely ready, just in case."