Prime Minister Boris Johnson on Tuesday called Captain Sir Tom Moore an emblem of global hope after the fundraising lockdown hero contracted Covid-19 and died aged 100.

Downing Street said Johnson had spoken with one of Moore's daughters and had ordered the British flag above Number 10 to be flown at half-mast.

"He became not just a national inspiration but a beacon of hope for the world," Johnson said in a statement.

Capt Sir Tom Moore: WWII veteran who walked into record books

Captain Sir Tom Moore, who has died aged 100, became a national hero in Britain by walking laps of his garden during last year's coronavirus lockdown to raise funds for healthcare charities.

By the end of the feat, the World War II veteran had raised a record-breaking £33 million ($45 million, 37.4 million euros).

But when he set out on his sponsored walk, Moore's aim was modest: to raise £1,000 as a "thank you" for the treatment he received for skin cancer and a broken hip.

He set a goal of completing 100 lengths of his 25-metre (82-foot) garden in Marston Moretaine, between Bedford and Milton Keynes in southern England, by the time of his 100th birthday.

But his walk captured the public's imagination and the donations kept rolling in, so much so his JustGiving website page crashed. 

Beacon of light

The image of the stooped but dapper veteran, leaning on his walking frame and rarely seen without shining military service medals pinned to his blazer, and a regimental tie, was a rare good news story in a gloomy year.

It gave the public hope and helped galvanise Britons' gratitude to the state-run National Health Service (NHS), and the need to help others at time of need and uncertainty.

"In the last war, it was soldiers in uniform on the front line," Moore said at the time. "This time our army are the doctors and nurses (in) uniforms. We will survive this."

He added: "They have done incredible things for me and my family, and I am glad that I have been able to give something back to them, especially at this deeply challenging time."

His accomplishment turned him into an celebrity. Prime Minister Boris Johnson called him a "beacon of light" and a "true national treasure".

The final length of his garden on April 17 was met with a guard of honour from soldiers of the Yorkshire Regiment and was broadcast live on British television.

His 100th birthday on April 30 was marked by a Royal Air Force flypast, which was also beamed live across the nation. Some 140,000 people sent him cards.

In July, Queen Elizabeth II knighted the World War II veteran in a special outdoor ceremony at Windsor Castle, emerging especially from her own coronavirus lockdown for the occasion.

"This is such a high award and to get it from Her Majesty as well -- what more can anyone wish for?" he said afterwards. "This has been an absolutely magnificent day for me."

War to celebrity

Moore was born in Keighley, near Bradford, West Yorkshire, in northern England, and served as an engineer in India, Burma and Indonesia during World War II.

After his return to Britain, he worked for his family's building company and later became manager at a concrete company. 

In his free time he was a keen motorcycle racer and has admitted receiving a speeding fine while in his late 90s. He also appeared on a popular BBC television quiz show in 1983.

He wrote frankly about a sexless first marriage that ended in annulment. 

Although Moore was 50 when they met, he had a 40-year marriage with his second wife, Pamela, and visited her every day while she was in a care home with dementia.

In a BBC interview, he spoke of his distress about her mental deterioration and pity for other residents who had no visitors. 

After she died, he moved in with one of his two daughters.

In a whirl of activity since his walk, which inspired several other fund-raising efforts, he published an autobiography "Tomorrow Will Be A Good Day".

Praise flooded in from the public, sports stars, celebrities and royalty.

Chart-topper

The Yorkshire Regiment, into which the 8th Battalion Duke of Wellington's Regiment was subsumed, promoted him to honorary colonel in August.

The keen cricket fan was also made an honorary member of the England cricket team, had a train, several buses, a police dog, a Clydesdale horse and even a power boat named after him.

Somewhat improbably, a few days shy of his centenary, Moore became the oldest artist to secure a UK Number 1 single with his rendition of Liverpool FC anthem "You'll Never Walk Alone" with stage star Michael Ball and an NHS choir.

"My grandchildren can't believe I am a chart topper!" he said.

When plans were announced to make a film about his life, Moore speculated that Michael Caine or Anthony Hopkins would "do a wonderful job... if they were prepared to age up."