Thanks Doug
I haven't yet found any reliable information to say she existed but from what I've found so far, I think the first name isn't Fishtoft, that's the name of a Parish in Lincolnshire. Similarly the name of her husband William Coyne, is more likely to be Coney or Conny.
I did come across an Alice Bell married to Sir William Coney in FamilySearch but the only source is Ancestry Family Trees, so not a reliable source, but it might provide other search avenues.
The Visitation of London, p. 26 has a John Lambert of Kirton in Lincolnshire married to Joane dau of ____ Connye of Lincolnshire. John Lambert also has a sister Joane married to Philipp Conye. Again this might some other ideas about where to search.