The Priory of Finchelsea XI.

Christchurch, Greyfriars, London was built by Sir Christopher Wren in the 17th century. It was a perfect example of a Wren Church, with a tall, handsome tower and a long, beautifully-proportioned nave with high windows. The roof was suported by twin rows of columns, the pulpit of polished wood.
Then, as the phrase goes, 'Jerry dropped a bomb on it.' It was hit during the war by a bomb and reduced to a burned-out ruin.
Barsabbas was more than a little surprised that the Welsh professor had directed him to this place. A church he could understand, but a burned out ruin of a church was a rather odd thing. Yet the man had clearly said 'Christchurch.' And he'd mentioned a stained glass window. Surely the blasphemous order had actually updated their secrets since the Second World War?
"Christchurch?" he asked a broken-down drunk who happened to be passing. The drunk looked at the monk in his green and yellow habit.
"No."
Barsabbas sighed and began desperately to look for the stained-glass window.
His mobile 'phone rang, and he answered it.
"Barsabbas?" it was the Teacher.
"Master, I am in Christchurch, but there is no stained glass."
"You're sure?"
"Master, there is no glass at all."
"Barsabbas, haven't you considered that there might e more than one Christchurch in London?" the Teacher was being sarcastic. "I mean, it is rather a big city."
"Master?"
"A quick Google search tells me that there are two other possible candidates, Christ Church Westminster Bridge Road and Christchurch Spitalfields. Check them!"
"Yes, Master," Barsabbas said meekly.