Abbot Jonathan Coel,

I'm in a little over my head, but the gothic arches would suggest a time period for construction. Is that an image of St. Michael the Archangel on the left side of the picture?

Looks like it's in the 100-150 years old range of Gothic revival. If that speculation is correct, it's easy to see why it might be abandoned: it wouldn't be a highly graded historical building that would merit subsidies to maintain in the absence of a congregation that could maintain it itself. White elephants can be beautiful. (I should be clear that even high-graded churches can become redundant, though it's more likely that conservation efforts might be sought for them.)

Got it...
"Between 1106 and 1538 it was the church of an Augustinian priory, Southwark Priory, dedicated to the Virgin Mary. Following the dissolution of the monasteries, it became a parish church, with the new dedication of St Saviour's. The present building retains the basic form of the Gothic structure built between 1220 and 1420, although the nave is a late 19th-century reconstruction. [...] a cathedral only since the creation of the diocese of Southwark in 1905"

Link to virtual tour, http://cathedral.southwark.anglican.org/visit/virtual-tour

N.B. Of course just down the road is St George's Cathedral, Southwark
https://en.wikipedia.org/wiki/St_George%27s_Cathedral,_Southwark

Ah, Southwark's nave is a reconstruction from the 1890s....