It is thought they hid in the refurbished textile mill until late at night before committing the robbery and breaking out through the fire exit.
Among the Clarice Cliff ceramics taken were the unique Coral Firs Yo Yo vase and the very rare Summerhouse Conical shaped Tea for Two teaset, both of which were exhibited in the Liverpool Walker Art Gallery in their Age of Jazz exhibition in 2005.
Other items taken included three René Lalique bowls and an Etling bowl.
Also stolen were two bronzes by Josef Lorenzl, one 12 1/2in high (32cm), the other 14 1/2in (37cm) high, along with a third bronze and ivory figure by Barthelmy.
Mr Hewitt estimated that the stolen items had a combined retail value of around £70,000.
The theft occurred almost exactly a year after he set up at the Redbrick Mill. It appears it was a carefully targeted operation as no other shops within the centre were broken into.
West Yorkshire police are investigating the matter. Anyone with information should contact email@example.com quoting the crime number: 1308/314366.