Curious Window

This stained glass window is in a building down a ginnel a stones throw from the Minster glaziers workshops. I wonder if it was made by one of the glaziers in their spare time? The red lion is standing in front of a representation of one of the Bars or gateways in the city walls. I think it is most likely Monk Bar, and one day if I have the patience to decipher the 'back to front' writing or I get to go inside this building I might find out what it is all about!