Site: St Stephen's School, W2 (2 memorials)
W2, Westbourne Park Road
The school was founded and largely paid for by John Brooks, the father of Gothic architect James Brooks (1825–1901). One might expect a benefactor to chose his own son as architect for the work, though we can find no confirmation that this was the case here.
Saint Stephen's National School was opened in 1859 for mixed juniors and infants. Building enlarged 1897. In 1903 it had accommodation for 866 pupils. Architect Arthur Thomas Bolton was responsible for various additions to St Stephen's National Schools.
The 1856 construction of St Stephens church (nearby to the south east) was partly funded by the incumbent, the Rev. H. W. Brooks - who, it would seem likely, may be related to John and James Brooks.
Sources: Historic England (has a photo of the interior), St Stephens, Aim25, Westminster (downloads a pdf), The Victorian Web, ODNB.
St Stephen's church itself is just 2 streets away to the south-east.
Both plaques prominently carry the monograms MA (or AM) and DG (or GD) but we cannot explain them.