Credit:Alamy Although they are often referred to as the Emperor Heads, it is not known what the statues represent.Scott Allan Orr, from the School of Geography and the Environment, said the team wanted to understand how the figures have eroded to help the future conservation of the stones and other statues. The hunt is on to find up to seven Emperor’s statue heads that once stood in front of an Oxford landmark, one of which could be in your back garden.The stone figurines, known as the Emperor Heads, stand outside the Sheldonian Theatre and were first commissioned by Sir Christopher Wren in the 1660s.However, the current set seen outside the theatre are third generation and it is thought as many as 27 “retired” Emperor Heads could still exist.A team from the University of Oxford has located 20 but now they want to trace the remaining seven to study how they have weathered.The team believe that some of the statutes may be in private hands after tracing one figurine from the original set to the garden of a home in Oxford.Some of the other retired heads can be found in the grounds of Wadham College and Worcester College in Oxford with others at Harcourt Arboretum, Oxfordshire, and a north Oxford school. He told the BBC: “We think there should be 26 or 27 in total, not including the ones that are currently outside the Sheldonian Theatre right now.“What we want to do is use the old heads to try and understand how they have been weathered, how they have been deteriorated by time and that way hopefully we can inform the conservation and the management of the heads that we currently have, and other stone buildings around the city.”The first 14 heads commissioned were completed in 1669. In the early 1700s, one of the heads had to be removed to make way for the Clarendon Building, but the remaining 13 lasted 200 years until they were replaced in 1868.The current heads each weigh approximately one tonne and were commissioned from Oxford sculptor Michael Black.The team has asked people who believe they have one of the missing statues to get in touch by contacting Professor Heather Viles. Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings.