A little-known village on the outskirts of London is preparing to mark Anzac Day this weekend, as it has done for generations.

Harefield, in Middlesex, was the site of an Australian World War I hospital, and more than 100 diggers who died there still lie in the village cemetery.

"I am amazed at the amount of Australians who came over to fight for what was, at the time, 'the mother country'," church warden Rowena Scott said.

"I think it's a real privilege that we have actually got some Australians buried here and we can actually honour their names and remember them ... let them not be forgotten."

It all began when ex-pat Australian Charles Billyard-Leake donated his manor house to the Australian Government to use as a wartime hospital.

Nurses arrived from Australia to prepare for the first patients who began to arrive from the Western Front in June 1915.

As increasing numbers of casualties were admitted, a series of huts was erected to accommodate them.

At its peak, Harefield could accommodate 1,000 patients and by the end of the war, a staggering 50,000 injured diggers had been treated there.

Anzacs laid to rest in hospital cemetery

Among those treated was Sergeant Thomas Regan from Camperdown, Victoria.

The keen sportsman enlisted in the local Light Horse brigade and landed at Gallipoli in 1915, but his active service was to be short-lived.

Regan spent eight weeks in the trenches before falling ill with dysentery and later tuberculosis.

Anzac Sergeant Thomas Regan died of Tuberculosis in 1916 while being treated at Harefield Hospital. ( Supplied )

Thus began a long journey via Malta and London to Harefield Hospital where the Sergeant was admitted on June 5, 1916.

Weeks later the 27-year-old was dead.

His obituary in the local newspaper in Camperdown noted that his parents received a letter from the matron at Harefield telling them he had taken a "bad turn".

As a result, wrote the matron, "he never rallied and gradually sank until he passed away".

The matron wrote that Regan was buried "with military honours on Tuesday afternoon in the little cemetery where two of our other patients have been laid to rest".

By war's end, more than 100 diggers would have died at Harefield, along with one Australian nurse, Ruby Dickinson, who succumbed to pneumonia in June 1918.

Thomas Regan's grave lies at the back of the Anzac cemetery, nestled among the picturesque grounds of St Mary's parish church.

His parents William and Maryanne Regan later received a parcel from Harefield containing their son's personal belongings, including a comb, diary, rosary beads, a biscuit tin and four handkerchiefs.

Villagers would come out to walk the mile from the hospital to the cemetery, accompanying the bodies of those who had passed away at Harefield on their final journey.

A Union Jack which was draped over the coffins was later donated to Adelaide High School, which still treasures it.

The flag has been recently restored but is still too fragile to display again.

This year, Regan's niece, Vera Regan, and great niece, Judith Murfitt, will pay respects to their uncle and great uncle in Gallipoli on Anzac Day.

The pair, who still live in Camperdown, won tickets to travel to Gallipoli in a ballot.

'I was brought up to be thankful for what the Australians did'

Local Harefield resident Joan Goodman remembers her father, who was a teenager at the time of the war, talking of the military burials.

"The village was so small that it really was quite a large population of them. I know my father did used to go sometimes down to their funerals," Ms Goodman said.

Ms Goodman also remembers hearing from her father that the village children would go to the hospital.

"He told me when they were young they used to go over to the hospital to visit the soldiers, and probably play games with them, just went over to break the day up for them, because they didn't have any visitors from home".

As she has done since she was a young child, Joan Goodman will go to St Mary's church for the Anzac service this weekend, during which children from the local school lay flowers on the graves of the Australian soldiers.

"I was brought up to be thankful for what the Australians did for us, you know helping us with the war and things," she said.

Harefield never returned to its original state as a private home and remains a hospital to this day.

Following the war it became a sanatorium for tuberculosis patients, later morphing into a hospital specialising in heart and lung conditions.

It was at Harefield in 1983 that Magdi Yacoub performed the UK's first heart and lung transplant and Australians were among the patients.

"This hospital functioned as a referral hospital for Australians with heart-lung conditions," Sir Yacoub said.

"[Those] who required heart-lung transplantation, we looked after them and they went back to Australia.

"So the Australian connections linger on," he said.

'It's a magical place'

Today Harefield is home to state-of-the-art cardiac catheterisation laboratories.

Hundreds of patients are treated each year for heart blockages and heart attacks.

The original manor house has fallen into disrepair and its future is uncertain. The huts built for the Anzacs are long gone.

What remains is, from the outside, a rather drab collection of brick buildings and pre-fabricated annexes.

But just as was the case 100 years ago, it is what goes on inside Harefield that is so special.

"In all honesty, it's a magical place," consultant cardiologist Mark Mason said, who has worked at Harefield for about 20 years, a place he thought initially he would stay for just a month.

"There has always been a 'can do' attitude here. No problem is insurmountable, nobody is beyond consideration.

"They may ultimately prove to be beyond salvage, but nobody is beyond consideration and everybody is given their best chance."

Australians too were given a chance at Harefield. Even those who did not make it are still here — never forgotten by this small English village who took the Anzacs to their hearts.

You can learn more about Harefield Hospital's WWI centenary activities here.