I don't have a connection directly but I have an interest in Gawnes. I had two candidates for Thomas, the other being the son of John Gawne and Ann Kneale, chr 25 Mar 1821. I was swayed towards the latter by the presence of nephew John J. Cowen/Cowin of Bride in the 1901 census. If he is the son of Margaret Gawne and Thomas Cowin then Margaret could be the sister of Thomas 1821...chr 21 Mar 1824 Bride...daughter of John Gawne & Ann Kneale.
I haven't worked on this for quite a while but it is an angle that you might like to pursue.
Ah but, I hear you say, Thomas 1821's parents are given as Thomas Gawne & Ann Kneale. There's no marriage for a Thomas Gawne to an Ann Kneale but there is a John Gawne-Ann Kneale marriage in 1813. They had Ann 1805 (illeg), John 1813 [m Elizabeth Corkan], Catherine 1816 [m. John Clague], Jane 1818, Thomas 1821 (probably) and Margaret 1824 [m. Thomas Cowin].
I could be barking up the wrong tree entirely but if you do want to look into this and manage to find anything one way or the other do please let me know.
Thanks....Jane