There will be no Christmas tree in Ron's cramped, tiny room this year. There are no fairy lights, no piles of presents, nothing to drive out the loneliness.

Another Christmas without his children is almost more than Ron can bear. So this year he has decided to ignore it. It is the only way he can get through it at all.

Five years ago, Ron lived in a four-bedroom house with his partner and their two children. He ran his own business and was happy to be a family man.

Things might not have been perfect but the sight of his daughter and son squealing with excitement as they unwrapped their Christmas presents would always flood him with an overwhelming feeling of love.

Ron hasn't spent Christmas day with his children since 1998. Now, all he has left of them are a few photographs. He hasn't seen his nine-year-old son for two years. It is four years since he saw his 12-year-old daughter.

The photographs are starting to get tatty. They are five years old. They are the only thing that connects Ron to his children but his children do not look like that now.

He longs to see his children and thinks about them all the time. But there are legal issues involved and both Ron and his ex-partner have fought bitterly in the family courts.

Ron recognises there are two sides to these stories and accepts that in the ugly fallout of a rancorous break-up, no one is free from blame. But he says his children should not have to grow up without the love of their father.

Until this summer his son and daughter went to school at the bottom of his road on the outskirts of Worthing.

He said: "When I came out of the house in the morning, sometimes I could hear the schoolkids in the playground. I would imagine my children running around in there and wonder what they were thinking about."

Now they have moved schools, he doesn't even have the comfort of knowing they are close by.

Ron is one of thousands of fathers who won't see their children on Christmas Day because keeping in touch has been made difficult for them or contact rights have been denied. A group of almost 200 parents and grandparents marched on the Lord Chancellor's department last week in protest at the family courts' bias against non-resident parents in contact disputes.

The march was organised by new fathers' rights group Fathers4Justice, which campaigns on behalf of fathers who want equal parenting rights.

The Coalition for Equal Parenting was also involved in organising the December 17 protest. It claims many non-resident parents are denied access by the family courts under the direction of the Lord Chancellor.

The coalition also claims courts do not have enough power to enforce contact orders once they have been granted.

A spokesman for Fathers4Justice said: "Court orders issued by family court judges are simply not worth the paper upon which they are written.

"It is indeed a shock to discover that after huge expense, often running into tens of thousands of pounds, and months or even years of litigation, it all counts for nothing.

"Daring to ask the court to enforce its own orders generally leads to the mother's legal team (often legally aided) describing the father as a vexatious litigant. Ninety per cent of the time it is the father who is the non-resident parent so this is essentially a bias against fathers."

Ron says his own experience has followed this pattern. Now he can understand why 40 per cent of non-resident parents lose contact with their children after two years.

"I know neither of my children have ever got the birthday or Christmas cards I sent them. If their mum won't let me see them, I can't believe she would let me send cards.

"There isn't much else I feel I can do right now. I lost my business partly because of all the time and money I spent in court so I'm not in work at the moment, which makes things even more difficult. You can go back to court time and time again but ultimately there is no way out.

"It's like a bereavement but you can't grieve properly because you know your children aren't dead.

"The last time I saw my kids was nine months ago, when I was coming out of a T-junction on the A24. I was looking to my right and out of the corner of my eye I saw my ex-partner's car turning in. In those brief few seconds I saw my son. I think he waved at me."

Ron, 46, believes his children are suffering without him.

"I worry about the way this is affecting my kids. Studies show that children who grow up without a father are more likely to turn to crime or to end up in a broken home themselves. I worry that my son might end up in prison or my daughter could get pregnant in her teens. And I won't be there to help."

This is the fear that haunts many non-resident fathers.

Daniel Piggott is the father of a 16-month-old boy who lives 20 miles away from his Steyning home.

He said: "I worry about how it will affect my son not to have his dad around. Fathers play a crucial role in their children's lives."

Daniel has negotiated to see his son for an hour and a half every weekend but he would love to spend more time being a proper dad.

Again, Daniel knows he has caused hurt and upset to his ex-wife.

They split up before his son was born and she understandably felt betrayed and angry.

But when IT consultant Daniel moved back to his parents' house, they couldn't come to an agreement on access arrangements. He has now been to court four times to fight for the right to see his son.

Daniel, 29, said: "I didn't know anything about the system or the raw deal fathers get until I was caught in the middle of it.

"Last Christmas was my son's first Christmas and I spent it without him.

"I had lost everything. I felt like my life was barely worth living.

"I have missed all the milestones - his first steps, his first words. I just want to be around for my son but I'm being prevented from spending proper time with him. I don't want to be just a McDonald's dad."

This year Daniel has negotiated three hours with his son on Boxing Day.

"To most people that would sound like nothing but to me it seems like a really long time. To me it's the be all and end all of everything."

There can be happy endings to these sad stories.

John Baker, a lecturer in applied social studies at Brighton University, has finally come to an amicable arrangement with his ex-wife about seeing his 16-year-old daughter and 15-year-old son.

The teenagers live in France, which makes contact difficult, but John spends every second Christmas with them. Their mother actually moves out of the house to make way for his visit.

John, 57, who lives in Hove, said: "Some fathers will be spending Christmas in poky rooms knowing their ex and her 'new man' will be enjoying themselves with the children in the family home.

"For a while my situation was that extreme. We split up on May 11, 1990 and for the first few years my ex made it very difficult for me to see the children.

"But I stuck in and refused to walk away. I can see why many fathers would think it was for the best to let the family get on without them but I refused to accept that idea.

"My children also played a big part in helping to make things better. From the start they made their views clear, even though they were small. It was a brave thing for them to do, to make a stand like that. It made a big difference.

"It took probably four or five years for the anger to bed down but now things are finally amicable between us. You get so wrapped up in your immediate pain when this is happening that it's hard to see past the end of next week, never mind to the next ten years. But there is hope."

Ron doesn't feel much hope this Christmas, though. His family and friends tell him the children will make contact with him again when they are in their teens.

But Ron had a heart attack in his late 30s and needed a bypass operation. He doesn't know if he will live long enough to re-establish contact with his kids.

"I know the pressure of all this is slowly killing me. People say 'your kids will come back to you one day' - but what if I am not around for them to come back to?"

For help and advice contact www.fathers-4-justice.org or www.equalparenting.org or Families Need Fathers, 134, Curtain Road, London EC2A 3AR, telephone: 0207 613 5060 or log on to www.fnf.org.uk