
Harrison's wealth provided his new church with superb interior furnishings including an exquisitely carved and painted wooden screen. The decoration of the screen is exceptional and includes floral designs, human heads, hearts, animals, and grotesque likenesses.
There are further exceptional carving decorating the pews, pulpit, and wall panelling. The ceiling has lovely decorative plasterwork, and there are beautifully carved corbels depicting angels playing musical instruments, among other themes.
The stained glass is not original; much of it dates to the Victorian period. One window is commemorated to Harrison and shows him directing the construction of the church. The church is full of monuments to prominent local citizens. The church was sensitively restored in the 19th century by Norman Shaw.
St John the Evangelist is no longer in regular use and is now cared for by the Churches Conservation Trust.