[5] In 1898 the North Eastern Railway (NER) chose Field as architect for their new main headquarters in York, now the Grand hotel.
[6] Field also received the commission to design the NER's London offices at 4 Cowley Street, Westminster, his plans were submitted 1904 and the building completed 1906.
Amos was architect for the builders William Willett and Son, for whom the practice produced designs for several large London houses, and apartments.
Mary Field's friendship with Elizabeth Garrett Anderson and her circle of friends led to him becoming the consulting architect to the New Hospital for Women on Euston Road from 1888 to 1905, where he designed a nurses home (now demolished) at the rear of the building.
His last built design was in 1941, as a favour for his cousin Daisy Field, at Great Dixter, for a conversion of a store attached to the oasthouse into a cow house.
[10] He died on 16 June 1948[11] and is buried with his wife Mary Frances (1859-1950) in the churchyard at St Michael's Playden, Sussex.