Site

We visited on a Sunday and there was a religious service taking place. But Serviced Office Portal has this address advertised as "Located in Bethnal Green, in a church hall, which has been converted into a multi-use co-working space." The photos there show a large panelled room with an arched roof. Perhaps the office space is on the first floor and the ground floor still has a religious function.

In our photo the foundation stone is to the left of the umbrella. The war memorial is the large white panel framing the pedestrian's head.

St Peters church Bethnal Green is the one close to this plaque.

LMA's page for St Thomas church gives the address as Baroness Road: "The church of Saint Thomas was constructed in 1848, designed by Lewis Vulliamy. The building was financed by William Cotton as a memorial to his son. In 1844 a parish was assigned from part of the parish of Saint Matthew. The church was damaged during the Second World War and demolished. The parish was united with Saint Peter's." 

This 1895 map shows that Baroness Road had only one church, and it is indeed labelled St Thomas's.  However we thought that was built as part of the 1859 Columbia Market development and that the architect was Henry Darbishire. Seems we were mistaken.