She had longed desperately for a baby since her marriage 15 years ago.

So powerful was her dream of starting a family that Linda Weeks and her husband Richard spent more than £21,000 on fertility treatment without success.

At the age of 54, many would have given up all hope.

Ticket to pride: Linda Weeks cradles her daughter Katy, born after an anonymous woman came forward to donate eggs

But not Mrs Weeks.

Instead, she took the extraordinary step of advertising for an egg donor on buses across London.

To the couple's joy and amazement, that last throw of the dice worked - and a year later they are the proud parents of Katy, born on June 3 at 5lb 11oz.

Yesterday, speaking for the first time since the birth, Mrs Weeks said no words could describe her gratitude to the woman who came forward to donate eggs.

Doting parents: Richard and Linda Weeks tried unsuccessfully for 14 years to start a family

'Thank you seems inadequate,' she said.

'We will be grateful for ever. She is fantastically generous. It is such a wonderful thing to do.'

Mr and Mrs Weeks, from Maidstone in Kent, will not meet the anonymous donor.

Mrs Weeks, now 55, said: 'It would be wonderful to know what made her come forward but we will never know.'

Mrs Weeks, a librarian, and 50-year-old computer programmer Mr Weeks, spent £2,000 placing the ads for a month on 50 buses.

Desperate plea: Mr and Mrs Weeks advertised on 50 London buses for an egg donor to come forward

They showed a photograph of them on their wedding day in March 1993 and read: 'We'll never be Mummy and Daddy unless a wonderful woman aged 36 or under can help us by donating some of her eggs.'

Mrs Weeks had previously tried placing less detailed adverts in newsagents' windows, but none yielded a suitable donor.

The ads on buses generated a great deal of media attention, however, which helped prompt a donor to come forward.

Some 96 women expressed an interest but only one went ahead last year and Mrs Weeks was treated at the London Fertility Centre and the city's Logan Centre.

It was just in time.

Although there is no official age limit for IVF in Britain, doctors do not treat those over 55 and the NHS will not fund treatment over the age of 39.

Mrs Weeks' case has renewed calls for egg donors to be paid so more might come forward.

She added: 'It is still hard to believe that Katy is really ours. It is just wonderful.

'It is the best news that we could ever have.'