There was a head-scratching moment when Martin Swales answered his front door and a priest handed him a letter.

The mystery was quickly solved. It contained a thank you note from someone whose life Martin had saved.

He knew his bone marrow had been given to someone called Jan and imagined it was a woman in Britain.

In fact the recipient was dad Jan Zemek 4,500 miles away in the US.

And Martins gift of life has led to an extraordinary 30-year bond between the pair, who are like blood brothers.

Jan named his second daughter Martina in honour of his hero and Martin is godfather to his third girl.

Retired welder Martin, 58, of Guisborough, North Yorks, said: Donating bone marrow didnt just save Jans life, it changed mine as well.

The first time I met Jan, I put my arms around him and he hugged me back.

It felt natural, like I was welcoming my brother. It feels like our two families have become one.

They each have three grown-up children and have visited each other for baptisms, graduations, and weddings.

Martin recently went to Switzerland, where Jan lives with his family, to celebrate 30 years since the transplant and present his blood brother with a Walk of Fame plaque.

It includes the touching message: Stood strong, fought hard, and won. You are a survivor.

The mens amazing and heart-warming story dates from 1986 when Martin joined the Anthony Nolan stem cell register after an appeal to save two girls living in the North East.

He was not a match for the girls but in 1989 was called by the register because he could be for Jan.

Martin said: It was quite a shock because Id pretty much forgotten about the register. They told me I was a possible match for someone and what was involved. I said yes straight away. I wanted to help if I could.

Despite the discomfort, Martin gave bone marrow from his hip at a clinic in Harley Street that August. Doctors extracted it from inside his hip using a long needle. Today most donations are no more invasive than giving blood.

Martin spent two nights in hospital. He said: It doesnt take long but at the time I was suffering from sciatica so I think I found it a bit more painful than most. It was an uncomfortable journey home on the train.Anthony Nolan covered the cost of the trip.

Jan, a 27-year-old dad, was diagnosed with leukaemia in 1987. Initially doctors kept the news from him as no treatment was available in the Czech Republic, where he lived.

Jan said: I was diagnosed one year after the Chernobyl tragedy, weve never known if that radiation was to blame for my cancer. I suddenly grew very tired, nobody knew the reason.

I didnt know how sick I was because the doctors wouldnt tell me.

My wife, who was then my girlfriend, went to the same doctors and they told her, Dont marry this guy, dont have children with him. He is going to die in two years.

But Radka ignored their warning and insisted on marrying Jan in 1987.

His only hope was a bone marrow transplant. Weeks later he left for the US with his dad, who planned to be his donor.

Jan said: A few months earlier, I read in the paper the opera singer Jos Carreras was diagnosed with a similar blood disease and was going to the same US centre for a transplant.

They arrived with less than 40 in their pockets and discovered a transplant from his dad would give Jan only a 15 per cent chance of survival.

Instead doctors advised them to find a donor. It took two years and 10,000 to test potential donors before they found a perfect match in Martin.

By then Jan and Radka had become parents to their first daughter, Jana.

Jan needed to raise more than 100,000 to fund the transplant.

He said: It was such a huge amount of money to raise but when you are dying you have no choice.

There were 12 rival local radio stations but they all got together to run a joint appeal, which they broadcast at the same time. It was incredible.

Jan did a sponsored run, gave talks about his ordeal to church congregations to request donations, and wrote to celebrities, especially those with links to the Czech Republic.

Donald Trump s ex-wife Ivana gave 1,000, as did One Flew Over the Cuckoos Nest director Milos Forman. Jan said: The response was crazy. So many people donated 20 dollars or 50.

Martins bone marrow was flown to the Fred Hutchinson Cancer Research Center in Seattle, where Jan was waiting in an isolation room.

He had been blasted with chemo and radiotherapy so his immune system would not attack Martins transplanted cells.

Normally, under strict anonymity rules to protect donor and recipient, Martin and Jan would have been unable to contact each other for years.

But a priest from the North East of England working at the hospital recognised Martins address when the bag of bone marrow arrived.

He offered to take a photo of Jan, a thank you letter, and a Czech garnet stone to Martin when he returned home in 1990.

Martin said: I was stunned. I had no idea my bone marrow had travelled so far. Knowing Id helped a young father, just like me, brought home how important it was and how easily it could have been me waiting for a stranger to save my life.

I wrote straight back. The priest also brought a letter from a couple whose daughter was in the same hospital.

Her transplant didnt work. Sadly she died, but they wrote to thank me for saving Jan. Responding to them was much harder. How do you find the right words?

Martin and Jan kept in touch. When Jans second daughter was born in 1991, he and Radka named her after Martin.

Jan said: How do you repay someone who saved your life? Naming our daughter after Martin was our way of showing him we would never forget what he did for us.

Hes not just the man who saved my life. He is a nice guy. Thats why were so close.

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Jan, 59, and his family moved to Switzerland, where he landed a job with a sports marketing firm that works with World Athletics.

In 1992 his job brought him to Crystal Palace in South London and he spent a few days with Martin and family.

Jans youngest daughter Michaela was born in 1995 and he invited Martin and his family to Switzerland for the baptism and asked him to be godfather.

The two families continued to visit each other and holidayed together in the Czech capital Prague. When Jans eldest, Jana, was studying at Newcastle University, she regularly spent weekends with Martin and his wife Tracey.

Martin said: It meant so much to visit Jan for the 30 anniversary of his transplant earlier this year.

"They showed us the sights and we went up the mountains. It was brilliant. I could never have imagined this when I joined the stem cell register all those years ago.

He added: I hope Martin and I will be able to celebrate another anniversary together in ten years.

The Anthony Nolan register matches potential donors to patients needing stem cell transplants and does vital research. To join, donate or find out more, see anthonynolan.org .

Read more:
Moving story of bone marrow donor's amazing 30 year bond with the man he saved - Mirror Online