A re-analysis of sculptures from the site suggests instead that it was constructed on the orders of a native Celtic British king, who wanted to thank the Romans for occupying Britain.
Dr Martin Henig, of Oxford University's Institute of Archaeology, now believes that the baths - and the temple complex of which they formed a part - were built to glorify two of the Romans most responsible for the conquest of Britain.
They were Claudius, who was emperor at the time, and his most promising young general, Vespasian, who became emperor later and was on the imperial throne at the time when the temple complex at Bath was being constructed.
Dr Henig's research, which is based on historical and archaeological evidence, suggests that the temple and baths were built by late-first- century Britain's most important native British political leader, the enthusiastically pro-Roman king of the Sussex-based Atrebates tribe. This local monarch, Togidubnus, had benefited immensely from the Roman conquest. His kingdom had been allowed to retain its autonomy and the Romans had even awarded it extra territory; this almost certainly came to include Bath itself.
Dr Henig's re-analysis of the sculptural and architectural motifs from the Bath temple has identified key iconographic evidence. By studying other monuments around the Roman world, he has concluded that stars sculpted in relief on the exterior of the temple represent a deified emperor - probably Claudius, the Roman ruler who instigated the conquest of Britain. The Romans liked to believe that their rulers quite literally became heavenly bodies after they died.
Many other sculptural motifs at Bath may have been designed specifically to glorify Claudius's and Vespasian's roles in occupying Britain.
The Roman take-over had involved the conquest of the sea - the crossing of the often turbulent Channel - a fact which, Dr Henig believes, is commemorated at Bath by images of the maritime god Neptune and his half- fish, half-human courtiers.
Victory on land - Roman civilisation's subjugation of hostile tribes in Britain - is commemorated at Bath, he says, by a relief sculpture of a shield of virtue held aloft by two winged female figures representing military victory. In turn, they stand on globes (symbolising Earth) encircled by the orbits of the planets - a clear reference to the Empire's divinely ordained authority over both the world and the cosmos.
What's more, Vespasian's imperial role as the people's saviour is symbolised, says Dr. Henig, by two reliefs of special "civic crowns" made of oak leaves and acorns.
Even the choice of god to whom Togidubnus dedicated the Bath temple was probably determined by political considerations. For the wily British ruler chose to dedicate the complex to one of Vespasian's favourite deities, the Roman virgin goddess of wisdom, Minerva. A new analysis of Vespasianic coins has revealed the emperor's liking for the goddess. His whole family were Minerva enthusiasts, and Vespasian's younger son, Domitian, was obsessed with her. He even had a statue of her in his bedroom - and believed himself to be Minerva's son by immaculate conception.
"I believe that the Bath relief sculptures should now be viewed as the only substantial surviving iconography in this country commemorating the Roman conquest of Britain," says Dr Henig.