Hi, Jack:
I've really no idea! I've not taken the line to that era, except in the USA.
John GILBERT (1577 Eng - 1657 USA) was the son of Giles/Gyles GILBERT and Joan PEARCE.
Giles is said to be the son of Robert GILBERT (d. 1546 Bridgwater, Soms., England) and Jane HAYDON (b. 1478 England). I've yet to research them.
Alice HOPKINS, second wife of John GILBERT, is to be the dau of Thomas. Literature has him of Bristol but I've yet to find good info.
Several HOPKINS in the area of Churcham and Wotton-under-Edge (where I find an Alice born to Thomas with a date most trees list), seem to have to do with weaving, haberdashery, and the like.
If it would help you, the other male child of Giles and Joan was Giles (1573). I haven't followed him further.
Giles is the only child I have in my tree for Robert and Jane (Haydon) GILBERT.
John GILBERT, with third wife Winifred (Rossiter) COMBE, had sons Gyles and Joseph.
There is a lot of information on the GILBERT family online.
NEHGR 4:339 on has a lot on the family but concentrates on John, sons, and later generations here in the USA. It might be helpful, though. There is also a genealogy in both Old and New England at:
https://archive.org/stream/genealogicalmemo00thor#page/n3/mode/2upSo sorry, Jack, that I'm not much help. My England information is too early to likely be of use to you.
Cheers!