This week is roughly the date of their first jam, where Jimmy Page, Robert Plant, John Paul Jones and John Bonham rehearsed on Gerrard Street, in London. By their own account, the chemistry was felt instantly as they blasted through Train Kept a Rollin'.

John Paul Jones: "We first played together in a small room on Gerrard Street, a basement room, which is now Chinatown. There was just wall-to-wall amplifiers, and a space for the door - and that was it.  Literally, it was everyone looking at each other - 'what shall we play?' Me doing more sessions, didn't know anything at all. There was an old Yardbirds' number called Train Kept a Rollin'... The whole room just exploded." (1990  interview)

Robert Plant: "I remember the little room, all I can remember it was hot and it sounded good – very exciting and very challenging really, because I could feel that something was happening to myself and to everyone else in the room. It felt like we’d found something that we had to be very careful with because we might lose it, but it was remarkable: the power.” (1990 interview)

Jimmy Page: "At the end, we knew that it was really happening, really electrifying. Exciting is the word. We went from there to start rehearsals for the album.” (1990 interview)

John Bonham: “We had a good play that day and it went quite well. Even the first time we’d played together, there’s a feeling when you’re playing whether it’s going to be any good, and it was good – very good indeed. But at that time I had no idea it would achieve what it has.” (Feb. 1972 interview)