One of London's most famous formal gardens is undergoing pounds 200,000 of work to restore its faded glory.

Berkeley Square, immortalised in music as the place where nightingales sang, is to have its centrepiece gazebo renovated at a cost of pounds 30,000 and floodlights will be introduced to illuminate the 200-year-old trees, reputedly the oldest in London.

A further pounds 140,000 has already been spent on new footpaths, drainage, floral displays, litter bins and signboards detailing the public square's 329-year history.

The most significant project in the Mayfair gardens has involved the restoration of a Victorian statue and fountain, The Woman of Samaria, created by the Pre-Raphaelite artist Alexander Munro in 1858 at the request of Henry Petty Fitzmaurice, the third Marquis of Landsdowne. The marble figure was initially positioned outside the square facing south but in 1937 was relocated looking northwards inside the garden. A few years later the fountain ceased to function.

The statue has now been cleaned and fitted with a granite bowl to catch water poured from the repaired fountain. The original basin was stolen more than 50 years ago.

Work on the sculpture was carried out by husband-and-wife team Will and Lottie O'Leary who cleaned the figure and constructed a marble spout to carry water into the bowl.

The project was funded by public subscription as a memorial to the late local businessman Victor Barclay, whose Rolls-Royce showroom overlooks the square. Donors include the Duke and Duchess of Marlborough, restaurateur Simon Parker Bowles and jockey Richard Dunwoody. The rest of the renovation project has been funded by Westminster council as one of the schemes under its environmental enhancement strategy, in which pounds 1,285,000 will be spent on improvements to parks and open spaces.

Peter Martindale, vice-chairman of the environment sub-committee, said the expenditure was a worthwhile investment to improve one of London's most beautiful squares.

Berkeley Square is named after John Berkeley, the Royalist commander in the Civil War and the first Lord Berkeley of Stratton, who acquired the land in 1675 shortly after moving into his new town house on Piccadilly. The garden was enclosed in 1747 when houses were built around it.

No 44 has been described by architectural historian Sir Nikolaus Pevsner as 'the finest terrace house of London and is now occupied by the Clermont Club and the society nightclub Annabel's.

Berkeley Square once featured an equestrian statue of King George III cast in lead by the French sculptor Beaupre. This had to be removed in 1827 when the weight buckled the horse's legs. Later the gazebo was set up on the site.

The square's trees were planted in 1789 by Edward Bouverie who lived at No 13, and are believed to be the oldest trees in central London. Other inhabitants of the square include William Pitt the Elder and Clive of India.

Although perhaps best known from the wartime ballad by Eric Manchwitz, A Nightingale Sang in Berkeley Square, the lyric owes more to poetic licence than fact. Historians are doubtful that the songbirds were ever found in the garden.