Brewer's: Leather or Prunella
It is all leather or prunella. Nothing of any moment, all rubbish. Prunella is a woollen stuff, used for the uppers of ladies' boots and shoes. (See Salt.)
Worth makes the man, and want of it the fellow, The rest is all but leather or prunella.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894