St. Andrew's Church, Biggleswade

This church contains some 13th and 14th century elements, but it has been remodeled and added to extensively over the centuries.

R.J. Withers designed the east-end stone reredos in 1877 and it was decorated with Venetian mosaics by Salviati in 1881.

Sources:
National Heritage
Rodney Burton on Wikimedia Commons
Derek Jones' flickr Photostream
Colin Hinson on Genuki

All Saints Church, Holton cum Beckering

This church is originally from the 13th century.

G.G. Scott renovated it twice, first in 1859-60 and then in 1870-74.

The reredos was designed by R.J. Withers. It contains mosaics of angels, as well as the Evangelists made by Salviati in 1867.

Sources:
Barr, Sheldon. Venetian Glass Mosaics: 1860-1917. London: Antique Collectors' Club, 2008. 121.
Wikipedia
J. Hannan-Briggs on Geograph
Richard Croft on Geograph
English Heritage