E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
John Roberts (A).
An enormous tankard holding enough drink for any ordinary drinker to last through Saturday and Sunday. This measure was introduced into Wales in 1886 to compensate topers for the Sunday closing, and derived its name from John Roberts, M.P., author of the Sunday Closing Act. (Standard, March 11th, 1886.)