I found the marriage date of Edward Berry and Elisabeth Forster as 23rd January 1766 at St Mary, Marylebone, London.
(Sir) Edward was the second son..the first, I gather was James. I have no record of a Thomas Berry as being one of (Sir) Edward's brothers.
Certainly the Berrys lived in London during their marriage.
By the way, Elisabeth Forster was born in Haleworth, Suffolk..the first child of Revd Thomas Forster.
I hope this information is useful.
david