Our navigator and I were in London on a weekend pass enjoying the experience when the Air Raid Siren sounded. A guy yelled there is a Bomb Shelter in the next block so we followed him on the run. The shelter was below ground and pretty well filled by the time we arrived. We were the only two in uniform. We found a place to set and wait it out like the others. We heard the explosion but do not know how close it was. After a fairly short period of time, the "All Clear" sounded. We departed the shelter and I couldn't believe how calm the people on the street were. They continued their walk as if nothing happened. They were hardened to this type experience.