Yes a broken pontil mark is no indicator of age in the collecting field of glass but with glasses of quality like these seem to be and the subject - a shamrock, rose and thistle we can safely assume that they are British glasses. So let me reiterate my point that no BRITISH wine / sherry/ glass would have a broken pontil mark post 1840-50 (of course there is exceptions like if they were made recently and I'm assuming that there is wear to indicate an earlier age which the op has failed to mention or the metal of said glass)