By Mukul Devichand
BBC Radio 4's Law In Action
Many a British baby has been conceived during hot, sultry nights on the Spanish Costa Del Sol.
There is a new trend for IVF conceptions
But now there is a new trend for procreation.
British couples are flying to Spain to take advantage of Spanish fertility laws by receiving anonymously donated eggs for their in vitro-fertilisation (IVF) treatment.
In the classic resort town of Marbella, I met an English couple who seemed the epitome of Brits on their hols but were guarding a secret.
They had not told friends back home they were coming and would not give me their real names. Why?
They were sensitive because after seven years of marriage and failed attempts at IVF back home, they were there to conceive a child using eggs donated anonymously by a Spanish woman.
"Hopefully the treatment we've had will be successful," said Heidi (not her real name). "That will mean a special bond with Spain for us and the child."
"But we're not going to tell the child where their genetic roots have come from."
Their story is increasingly common.
British couples desperate to conceive a child, flying to Spain to receive donated eggs.
Children born from donated eggs under Spanish fertility law will never be able to trace their genetic mothers, because there's a guarantee of anonymity for both egg and sperm donors.
In Britain, things are different. After a change to the law three years ago, children, once they reach the age of 18, can track down the donors of eggs or sperm that helped create them.
Egg and sperm donors are protected by anonymity under Spanish law
But the number of egg donors in Britain was already in decline. Critics say the change to the anonymity law has put off potential donors, leading to longer waiting lists for donor eggs.
Mary and Kevin Douglas found waiting lists of several years when they tried to find a donor egg in the UK.
"I had an early menopause when I was 22, hence the reason I can't have children naturally," said Mary.
Now in her thirties, she has been saving ever since for IVF.
But when she and her husband went to a local clinic, the waiting list for egg donors was "horrendous."
The UK clinic referred them to Spain, where they found an anonymous donor within months.
They know a few details about the donor.
"We know that she likes swimming and reading, and she's a waitress," said Mary.
"Well, I like swimming and reading, and I'm not a waitress but I am a kitchen assistant."
The couple say they have come here for private treatment purely because of the waiting list.
"We're not going to hide anything," said Kevin.
"In fact we're putting together a package of everything today, even our flight tickets."
Babies conceived under Spanish laws do not have the same rights British children now have, to track down their genetic parents later in life.
But if people can simply fly to one of our sister EU states for treatment, does the moral choice embodied in UK law have any effect?
"I think what we have done is put in place a regime that is effective," said Walter Merricks of the Donor Conception Network, which supported the UK legal changes.
"It is a principles based regime."
He believes it is not anonymity, but another legal difference which means there are more egg donors in Spain.
No member state allows payment for egg or sperm donation. But the amount of "compensation" allowed in Spain, at 1,000 Euros, is much higher than in the UK, and this may attract women to donate.
But a recent EU directive may force a change in this practice.
The impact of European citizens crossing borders to benefit from fertility laws is causing increasing concern elsewhere.
The European Society for Human Reproduction and Embryology, the leading professional association in this area, is now researching the impact across the continent.
But for couples desperate to have children, the possibility of treatment they cannot receive at home will always be a draw.
"I definitely haven't even thought about the idea of taking away the child's legal rights," said Peter, 40, who with his wife Sam, 39, has also travelled to the fertility clinic in Marbella.
"Something we have thought about though is if we waited until we're 46, 47, are we doing right by our children by picking them up on the bus pass?"
BBC Radio 4's Law In Action is broadcast on Tuesday 12 June 2007 at 1600 BST. You can listen to the programme for seven days after broadcast by clicking here.