the present building is a rebuild, as it was bombed in the war. The original must have been built around the 1850's, that was burnt down in 1898 (source: Spurgeon's Tabernacle website). The Portico seems to have survived the longest.
As I have gone 'map mad' lately having found extra links on this incredible site, one of them clearly had a building on it looking like a church and aisle etc. I'll have to search and try and remember which one it was!