By 1859, the AADD’s annual report described additional meetings in ‘St George’s school room, Southwark’. The schoolroom was attached to the church of St. George the Martyr, Southwark, whose rector was the Rev. William Cadman.
This is the church in about 1840
I can’t find any reference to a school room. Interior photos suggest that the lower windows weren’t for a downstairs, but were underneath the interior balcony, and as in most Anglican churches, what was under the sanctuary was the crypt.
It is possible, however, that the school room was connected to the nearby workhouse. The area was extremely poor. In fact, it was the site of the Marchsea debtors prison where Charles Dickens’ father was imprisoned. The prison shared a wall with the churchyard. Dickens lived nearby for a time, and knew the church well. He used the church as part of the landscape for Little Dorrit, where some scenesare set within the church itself.