I shouldn't generalize - always dangerous. I should have added.......C18 snapped pontils were quite substantial, a consequence of which was that feet were quite highly domed so that pieces would stand flat and the projecting pontil wouldn't get in the way. It's also true, I believe, that snapped pontils continued to be seen (although perhaps uncommonly) until something like 1820 - 1830.
I won't argue with Lustrousstone if a piece is marked Walsh etc., or known to be Bohemian - however, these feet are undoubtedly flatter than would have been the case with the C18 - and Fen's example looks to have a reasonably flat foot, so I guess we are looking at the C19.
Other factors should also be taken into account when assessing a possible date........I wouldn't expect to find stones etc. in Walsh, although quite likely in Bohemian.
One more question.............if this piece is 'flicked', does it have a lead glass ring, or perhpas just a dull sound?