Yes Dave, Hugh's mother was indeed a Dickey, I came across the reference to it in a Manuscript while looking at the Thompsons.... then I found yet another link between them and Swans!!
Thompsons and Swans (Hugh's daughters) both married into the same family, so I'm going to look at this other family's pedigree to see who else married into it, I'll keep an eye out for the Swans for you. Basically, one of Hugh Swan's (son of Hugh) daughters married, then their son married a Thompson in 1799...it gives the 2 Hughs being married to Dickeys!
So Hugh married a Dickey, then their son married a Dickey but it doesn't say if it was an Aunt/Niece or anything! You would need Matilda (Dickey) Swan's death cert to get her father's name etc..