LONDON -- The jury for Trafalgar Square was still out when Prue Leith got stuck in her traffic jam. The debate had shifted elsewhere, to other public art projects that had similarly raised hackles or won praise, like Anthony Gormley's "Angel of the North." This 20-meter-high statue erected in 1997 above the A1 motorway at Gateshead near Newcastle was controversial, but safely in the north of the country where it impinged on no one except the locals. Leith's idea to place a sculpture on the fourth plinth brought the debate right back to a place considered the symbolic heart of the nation's capital.

Knowing the stakes, the Royal Society of Arts gave her the go-ahead to proceed on the understanding that any project was to be of temporary duration and the public should be thoroughly consulted.

And so it was, through appeals and surveys launched in the media and those taken more formally with organizations, local councils and neighboring embassies -- anyone, in fact, with an official say or who overlooked the square.