These are not ceramic wellingtons but sockstretchers and were made by the pottery firm Wedgwood in the 1870s.
Sockstretchers were used at a time when people wore woollen socks, which were liable to shrink when washed. After washing, socks were put on stretchers so that they kept their size and shape when drying. Wooden stretchers were more common than ceramic.
With the increase in use of man made fibres during the late 1940s socks could be washed without shrinkage so sockstretchers were no longer needed.