ON a sunny afternoon, sitting at his home, it is difficult to believe 46-year-old Derek Emsley has terminal cancer.

Tanned and smiling, he looks the picture of health.

"If I'd had a pound for every time someone has said how well I look, I'd be a rich man," he laughs.

But his healthy appearance hides the awful truth of his illness. Derek has, at most, a year to live.

Tragically, the skin cancer he has suffered from for over a decade has spread to his spleen and lungs.

Doctors broke the news to engineer, Derek, of Leslie Avenue, Yeadon, last August. "When the doctor told me, he said: 'that wasn't what you thought I was going to say is it?' and I said, 'no it isn't, but if that's what it is then we'll just have to get on with it'. I'm an optimist you see."

This attitude is typical of Derek. He has twice had treatment postponed as it has clashed with dates for his beloved marathon running or fishing trips. A keen member of Aireborough Skyrac Athletics Club, he ran the recent Flora London Marathon in a 'disappointing' three hours and 28 minutes and despite beginning a new course of treatment on April 16, intends to attempt the notoriously tough Three Peaks Fell Race on Sunday.

"I have just started on the drug interferon and the side effects are pretty strong. It doesn't just affect you physically - making you want to sleep all the time and feel like you have flu - but mentally as well, you don't feel like doing anything, so I'll just have to see how I get on," Derek said. "I'm going to start the Fell Race but I can't guarantee finishing it. You have to complete it in a certain time or they pull you out for safety reasons, that's why I can't say I'll definitely complete it. But I'll certainly be giving it a go."

It was in the late 1990s when Derek was first diagnosed with skin cancer. A mole on his back had changed in appearance, but he delayed at first in having it checked out.

"You just keep saying, 'Oh I'll go tomorrow' and before you know it, a year has passed." It was another year after his first visit to the doctor before the mole was removed and the skin cancer was revealed.

"The doctor cut out the infected area and I had the all clear. But unfortunately some of the cancer cells must have broken away and affected other parts of my body. If I'd had it looked at earlier - who knows?"

The doctors at St James's Hospital in Leeds where Derek receives his treatment are hopeful about the effect of interferon on Derek's cancer. If it reduces the cancer, Derek could have up to a year to live. The family are just taking it day by day. "We'll just have to wait and see," he said.

Apart from the fishing and running, Derek plays darts and dominoes at his local pub, goes to the gym and to the pub quiz as he is still able to enjoy the odd pint.

"But we stay in on a Thursday 'cos we're boring," he said.

Derek and Jill have two children, Daniel, 22 and Janine, 21, both living at home.

The family are planning a holiday together after Derek's next scan.

Derek said: "The kids have taken it very well. When I first heard the news I said I wanted smiling faces, and I got them. They haven't let me down."

Meanwhile Derek is preparing for his fell running. Like fellow marathon runner and cancer sufferer Jane Tomlinson, who recently cycled from John o' Groats to Lands End, Derek is a keen fundraiser.

Jane's story was featured on the BBC Look North programme. She received treatment at the same clinic as Derek - at the same time. "Good luck to her I say," Derek said. "She's got a good attitude."

To date, with the marathon and the forthcoming Three Peaks run, Derek has raised £2,700 for the Macmillan Cancer Relief charity. Though Derek himself has a Macmillan nurse, because his health and state of mind are currently so good, there is no need for her to visit at present.

"The Macmillan nurses really look after you," he said. "After the marathon, they provided food and drinks and a massage."

Proud wife Jill said she has found the experience of the last year 'horrifying'. But she thinks Derek's attitude is excellent towards his illness. She said: "He still keeps up with his hobbies. He's always had a lot of interests and I think that is the problem for a lot of people - they just give up."

Until last September, Derek was still working as an engineer at Holly Park Rewinds in Pudsey. In fact, he was going to return to work after chemotherapy until the scan results showed the extent of his illness.

He has never kept a diary but the sitting room at his home is filled with his trophies won for fishing and running. On the wall behind him, photographs record for posterity his triumphant expression on completing the London Marathon.

"The photographs were to prove when I got old that I could run," Derek said. "If I ever had grandchildren, I could have said: 'look, grandad did used to be able to run'."

A week after the Three Peaks Fell race, Derek is going fishing in Ireland with his father and son, and has more trips planned for the summer.

"You have to keep going," he said. "While I'm running and fishing, I'm still living. If I stop, then I'm just waiting to die aren't I?"