LONDON - The old home phone numbers of former Prime Minister Harold Macmillan, composer Edward Elgar and poet John Betjeman are among millions being made available online for the first time on Wednesday.

Genealogy Web site Ancestry.co.uk has spent three years transferring nearly 2,000 old phone books to the Internet to help people research their family tree.

From the first slimline directory of 1880 that contained just 248 names to the heavyweight volumes of the 1980s, the collection traces the inexorable spread of the phone network.

While callers today would struggle to find Tony Blair's private number, anyone who owned a copy of a 1930s directory could reach former prime minister Ramsay MacDonald in Scotland.

His home address is listed with the old-style word and number combination, "Lossiemouth 3089".

In the 1941 directory for Tunbridge Wells, next to the listing for the Mac chain of fishmongers, there is an entry for "Macmillan, Harold; Pooks Cottage, Birch Grove. Chelwood Gate 81". He went on to serve as prime minister from 1957 to 1963.

Famous figures from the arts were also listed.

"Paddington 8630" was the number to ring the writer T.S. Eliot at his Regent's Park home in 1934, the year before "Murder in the Cathedral" was published.

Betjeman, could be reached at his Berkshire home on "Wantage 150", while Elgar is listed at his estate in Warwickshire.

Directories for London were published online last year. The project now includes all the 280 million historic names, addresses and numbers from across Britain.

Simon Harper, managing director of Ancestry.co.uk, said the collection will help family historians and those curious about who used to live in their house.

"It was an enormous undertaking to scan and index the 1,780 phone books," he said. "However, we believe that this resource will be of great interest and use to people around the world."