Julian Roup, a Bonhams expert, said: “There are three reasons that the vase is virtually priceless.
“The first is that there are only 15 other Roman vessels of this kind on the planet. The second is that there are 30 figures on it – the previous yardstick was the Portland vase with seven figures.
“This one too is complete, which is amazing considering how old it is and how fragile. The third is the incredible detail and craftsmanship of the figures… the musculature is so clear. The artist would have been enormously talented.