Quoted in The Beatles Anthology (George) ↑

We’d look around the cupboard

In Studio No. 2 there is a steep staircase that goes up to the control room. Underneath is a cupboard where they used to keep all kinds of different equipment. There were strange tambourines and Moroccan drums and all kinds of little things. The studio itself was full of instruments: pedal harmoniums, tack (jangly) pianos, a celeste and a Hammond organ. That’s why we used all those different sounds on our records — because they were there. So when we’d get to an overdub we’d look around the cupboard and see if there was something that would fit, like the funny drum sound on “Don’t Bother Me.”

George Harrison, as quoted in The Beatles Anthology (George)