It is, she says, her way of coping. 'Psychologically it helps me. It gives meaning to what has happened to me.'

Yet what has happened is almost beyond meaning. Beyond comprehension. Catherine's children were never returned from a holiday in their father's homeland of Germany. A protracted legal battle followed. Despite Catherine being their legal custodian, the German authorities ruled that Catherine should have no access rights to Alexander and Constantin until 2003 because it would be too traumatic - after so many years of separation, she had practically become a stranger to them. Despite repeated court applications to see her children, access arrangements were reneged, rulings failed to be enforced.

Time ticked on, years passed. More court cases, more rulings, more judgements. Until time finally ran out for Catherine. The courts ruled that it was too late to return Alexander and Constantin to England: the children had adapted to their new environment, they decided, and going back would be psychologically damaging.

Since their abduction almost eight years ago, Catherine has seen her children for a total of 24 hours. 'People say that what has happened can't be possible,' says Catherine. 'How can a mother be denied access to her children?' How indeed.

Local judgement
Tracing an abducted child can be extremely difficult, says Chief Inspector Tim Bonnett, co-ordinator for the UK Missing and Exploited Children Web Site which runs an international database of missing children. Unlike runaways, who usually operate alone, an abducted child is easily led by their parent.

'An abducted child will be in the care of somebody who has the mental capacity to hide them, to disguise them, to move much more freely,' says Chief Inspector Bonnett. He cites the case of one father who went on the run with his daughter for two years after setting up a new bank account, new credit cards and a new mobile phone. 'Basically, he was able to disappear and restart his life.'

The situation is further complicated when a child is taken out of the country, which often occurs when an international marriage breaks down and the parent flees to their country of origin. Although around 60 countries, including Germany, have signed up to the Hague Convention - which states that abducted children should be promptly returned to their country of habitual residence (the country they have been abducted from) - the vagaries of local judiciary systems mean this is not always put into practice.

'If a child is taken to a Hague convention country, an abduction case may be turned around in six weeks,' says Reunite's David Huxley. But, he says, if a country hasn't signed up to the Hague agreement, or if there are complications with local law, as in Catherine Meyer's case, weeks can turn into years.

Living in hope
'It's like a bereavement,' says David Huxley. 'And the longer it drags on, the worse it becomes.' One woman, whose children were abducted to Libya, was finally allowed telephone contact only to discover they could no longer understand her English accent. Other parents who are lucky enough to discover their children's whereabouts will never be sure if their cards, letters and presents have ever reached them.

And for parents whose children have been brainwashed to hate them, a reunion can be bittersweet as parent and child try to heal the rift. 'Often the child is told that their mum doesn't want them, that they will never see her again, or that she is dead,' says David Huxley.

'You end up being vilified by the abducted child,' says Catherine. 'My sons have probably heard bad things about me, and even if they try to think of positive images of me, they might begin to believe it was true. They may believe that I have abandoned them and no longer want to see them. Because surely if I loved them, I would be there with them. They don't know how hard I've been trying.'

And it isn't just the bereft parent who suffers. For Catherine, 'tug-of-love' is too simplistic a description for abduction cases. 'It's child abuse,' she says firmly. 'My children will be scarred for life and I, as their mother, failed to protect them. Every child should have the right to love and be loved by both its parents. Alexander and Constantin have been denied that right.'

As Mary packs away her son's unopened presents, the one thing she has left is hope. And Catherine, too, says that's all there is. 'Without hope you die. I hope my children will grow up and want to find out where I am. It is a huge risk. I'm sure they will take it but I don't know when. He can't keep my children hostage for ever.'

* Names have been changed

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