It is known locally as The Golden Boys after its colour, or The Carpet Salesmen after the partially-rolled-up plan of a steam engine which they are examining.
All three men were members of the Lunar Society.
Sponsored by an £8,000 bequest from Richard Wheatley in 1939, and £7,500 from the City Council, it was unveiled in 1956, from preliminary designs drawn up in 1938.
The statue was restored and re-gilded, and replaced in its old position in September 2006.
It is planned to be relocated; suggested sites including 'across the road' in Centenary Square or at Millennium Point in Eastside.