The Old Pretender. James F. E. Stuart, son of James II. (1688-1766.)
God bless the king, I mean the faith's defender; God bless- no harm in blessing- the Pretender. Who that Pretender is and who is king- God bless us all!- that's quite another thing.
Lambert Simnel and Perkin Warbeck, in the reign of Henry VIII.
Otrefief, a monk, pretended to be Demetrius, younger son of Czar Ivan Basilowitz II., murdered by Boris in 1598. In 1605 Demetrius “the False” became Czar, but was killed at Moscow the year following, in an insurrection.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894