FEAST is my one-name study, but unfortunately all my computerised records world-wide are currently inaccessible due to a hardware problem. I've had a quick look in some indexes which I have on disks, and there is some problem in identifying this family. I assume that the 1906 marriage certificate which you have is (GRO: Dec 1906 quarter, Cambridge 3b.1073) between George Feast and "Ada Nellie Bull otherwise Raynes"; I have a copy of this certificate in my files. Because her father Charles Bull was deceased and the two witnesses were called Raynes, I assume that she was brought up by them. George was in the Royal Navy.
There is a G. Feast, son of Robert William & Eliza Feast on the Doiran Memorial in Greece, who died 8 December 1915. The record states that he was the husband of F.G. Feast of 13 Caroline Place, East Road, Cambridge. He was a private in the Royal Irish Fusiliers. As his age is given as 49, this does not tie in with the marriage certificate unless some details were recorded incorrectly in either (or both).
Ada was married to Frederick J. Unwin in 1918 (GRO: Sept 1918 quarter Ely 3b.1308).
I am sorry that my computer hard disk files are not available for me to search at the moment, but if you can send me the details on any other certificates etc which you have, I'll do some quick searching for you and come up with something in the meantime. Send to my home email address.