Yes, Westminister Abbey was hit during a bombing raid on November 15, 1940. And yes, a section of the Lady Chapel was damaged. I don't go about blowing up churches for fun. Railroad lines on the other hand...
As for Allen's disbelief... the main thing that keeps RCSI secret is the fact that few folks actually believe what the agency is doing. It's kind of like how next to no one could see the unicorn for what she really was in The Last Unicorn. When most folks looked at her, all they saw was a white mare. It was only people who believed in magic, or were open to believing, who were able to see the real her. Allen will learn to see magic of course. It's just going to take a jolt to 'wake him up' so to speak.