Christ Church Southgate

Located in greater London, this church was designed in the English Tudor style by G.G. Scott and it was built 1861-62.

Three arched gables frame the mosaic reredos of Salviati's Last Supper, which is very similar to the one found in Westminster Abbey.

Update: More detailed photographs of the mosaic reredos have been added here.

Sources:
British Listed Buildings
Christ Church Southgate
Wikimedia Commons from Christine Matthews and John Salmon