Open-air concert project for passers-by to show off their musical skills

But this "street piano" — the first to be installed in a public music project — almost fell foul of the law. It is one of 30 that Londoners will find across the capital until 14 July in a arts scheme called Play Me, I'm Yours, part of the Sing London festival.

Passers by are invited to play the pianos and inspire sing-alongs in the street.

But just as the first person to play the instrument near Millennium Bridge had offered a rendition of New Orleans jazz, a police community support officer intervened to ask if it had an entertainment licence.

Fortunately, it was — and the music played on.

Martha Gowens, who is helping with the project, told the officer: "We have all the paperwork."

The PCSO relented, saying: "I thought you were collecting money, I thought it might be official but I had to ask."

The street piano project was conceived by artist Luke Jerram, who has already brought the instruments to Sydney, São Paulo and Birmingham.

The 34-year-old from Bristol said: "This is not about my ideas and ego — it is about people's creativity, and an opportunity to express themselves. It is a way to reach thousands and capture their imagination."

The pianos have been either donated or bought on eBay for about £100.

Once the project, in association with the City of London Festival, is finished they will be given to schools and community groups.

Each piano has been painted by artists to suit its location and provided with a song book.

A piano tuner on a bicycle will visit them regularly. The pianos will be chained to fences, railings or bollards — mostly to make sure drunks don't wheel them out into the middle of roads.

"The pianos belong to the people of London, including the drunk ones," Mr Jerram said. "The interesting thing is that you can't tell how someone plays until they sit down.

"Some people play wonderfully, and a crowd will gather, while others are just awful."

At the Millennium Bridge piano, tourist Georges Buzias, 73, from Paris, won applause from a small crowd that gathered while he was playing.

"I think it is a wonderful idea, très Anglais," he said. "I have been playing since I was about nine, but I have never seen this."

Where to tinkle the ivories

In the City from today

Paternoster Square
St Paul's churchyard
St Mary-le-Bow churchyard
Millennium Bridge, Peter's
Hill
Devonshire Square Estate,
Cutlers Gardens
Royal Exchange Buildings
Leadenhall Market
Smithfield Market Grand
Avenue
Liverpool Street Station
Middlesex Street Estate,
Petticoat Tower
St Mary Axe, opposite
Gherkin
London Wall, corner of
Moorgate
St Mary Aldermary, Watling
Street
St Bride's, Fleet Street
Browns, Old Jewry

Across London from 23 June

Lyric Square,
Hammersmith
British Library Courtyard,
Euston
Soho Square
Carnaby Street
Plaza Shopping Centre,
Oxford Street
Leicester Square
Church Street Market,
Lisson Grove
Maida Hill Market,
Harrow Road and Fernhead
Road
Portobello Market, under
Westway
Westbourne Triangle,
Westbourne Grove
Natural History Museum
East Garden,
Kensington
Tate Britain, Southwark