In 1924 a plan was submitted for an extension, including a south aisle,
vestries, Lady chapel, sanctuary, west porch and narthex, and completion of
tower. Eventually only part of this was carried out, with the south
aisle extension and the work on the tower being deferred.
However, a new sanctuary was constructed, giving a better sense of
proportion to the building, and the vestries and new porch were built. The
sanctuary roof follows on effectively in style from what was already in
place. The guide book says: Had this plan been carried out in its
entirety, St. Johnís would have had few equals of its size and period.