I expect you saw the George Martin documentary - much about Strawberry Fields on there if memory serves me correctly. I seem to remember something about unorthodox use of the mellotron's pitch adjustment knob..

Apparently the final mix of Dark Side of the Moon was quite a stunt too - I may have read about that in Nick Mason's biography - well worth a read.

I loved Kirsty McColl's version of 'Days' - yes, proper folk music ;-)