During the second war, servicemen were billeted in the buildings. The bombing of May 1942 destroyed the Almshouses and Chapel. Rather than clear the ruins, the City Council landscaped the ruins as a memorial to that dreadful night.
There are a few more details of the intervening history here
The glass panels contain pieces of crockery that were found in both the rubble and some older from around the grounds when things were being preserved.