Forgive me -- for some reason, my Usenet client posted a garbled version of the second half of my message, omitting the first half altogether. I will try again below:
On page 557 of volume 3 of Royal Ancestry, Douglas Richardson says that Jane (or Joan) Legh married, before 1522, Thomas Gerard.
Jane Legh's parents are given on page 557 as Peter (or Piers) Legh and his first wife Jane Gerard. On page 83 of the same volume, Jane Gerard -- "Jane (wife of Peter Legh, Esq.)" -- is listed among the children of Peter Gerard and Margaret Stanley.
Thomas Gerard's parents are given on pages 83-84 as Thomas Gerard and Margery Trafford. And his father Thomas Gerard is given on page 83 as a son of Peter Gerard and Margaret Stanley.
In other words, if all of this is true, and if I’m not catastrophically misreading or misunderstanding something, Jane (or Joan) Legh and Thomas Gerard, who married in 1522, were first cousins, both of them grandchildren of Peter Gerard and Margaret Stanley.
It doesn’t seem clear to me that it’s all true, both because of the first-cousin issue and also because most other respectable sources give Jane Legh, wife of Thomas Gerard, as a daughter, not of Jane Gerard, but rather her father Peter Legh's other wife, Margaret de Tyldesley. If this were in fact the case, it would preclude Jane Legh and Thomas Gerard being first cousins. They would still be second cousins, both being great-grandchildren of John Savage of Rocksavage and his wife Katherine Stanley, but that seems like this might have been easier to get a dispensation for.
It's irrelevant to the question of their consanguinity, but in the "Gerard" section of his Web presentation of the ancestry of Connecticut immigrant Oliver Mainwaring (
https://johnblythedobson.org/genealogy/ff/Mainwaring/Gerard.cfm), John Blythe Dobson notes that Jane Legh and Thomas Gerard divorced in November 1550. According to Evelyn Caroline Legh Newton's 1917 work The House of Lyme (widely said to be useful but less than perfectly reliable), this divorce was finalized 27 November 1550 and was due to Thomas Gerard's incorrigible infidelity.
So the question is, which of Peter Legh's wives was Jane Legh's mother? Were Jane Legh and Thomas Gerard in fact full first cousins, which seems unlikely? Were they second cousins via their Savage forbears, as seems pretty clear? And is there a record of a dispensation covering either of these eventualities?