Hi An65,
I am a descendent of Robert & Mary (nee Leighton) Gray.
Regarding; Silvester GRAY was almost certainly a relative, as is often expected of Romany ancesters, being the daughter of dinah Gray and Big Jim Shaw. She was bapt 1819 at Wickham, Ex, and was known as shaw aka thorpe.
My research is that the above Sylvester (Thorpe/Shaw/Gray) married Stephen Loveridge, b. 1820 Yowcester, Nothamptonshire, England. This Sylvester being a grandaughter of both Moses & Susannah Shaw as well as, Foundness & Mary Gray. Note Stephen & Sylvester are only around one year apart in birthdates.
I have as the Sylvester (Thorpe) Gray who married William Gray, son of Robert & Sarah (nee Harris) Gray, as being born around 1851 Burwell, Cambridge.
William Gray being born around 1839 Stoke, Ferry, is 20 years older than the Sylvester Thorpe/Shaw/Gray, bapt 1819 at Wickham, Exeter but, he is only around 12 years older than the 1851 Burwell, Cambridge, Sylvester Shaw. The male being 20 years younger than the female sounds a tad unusual even for a gypsy family where as the male being 12 years older than his female partner is more the norm?
I have seen other genealogy research stating what you have, perhaps I may be wrong ? I haven't for some reason got any parents for the Sylvester born 1851 Burwell, Cambridge, so I best look into that.
This same Gray family also had a tendency which is quite well researched to use the surnames of Gray, Thorpe, Shaw, Mobbs, & others regardless of their fathers surname of Gray. Sometimes they alternated throughout their lives just to make it harder & more confusing for us present days researchers & descendents.