MusicRadar says:

The BBC’s most celebrated sound effects unit was making synth-type sounds before synths had even been invented, being keen exponents of musique concrete (tape recordings were cut up, processed and edited to produce other-worldly tones). Delia Derbyshire’s oscillator-fuelled theme for Doctor Who is probably the most famous piece of music to come out of the Workshop, but its work and influence goes way beyond that.

Your votes:

“Delia Derbyshire was a significant pioneer of early electronic music before the days of Moog. She was recording electronic sounds onto tape and sequencing them from a barrage of reel to reel machines.Classic example being the theme to Doctor Who, composed by Ron Grainer who was himself to become a composer of electronic music along with everyone else at the BBC Radiophonic Workshop. I don't think anyone really understands the massive amount of work putting that theme together was.” (Thanks, bbcoz)

"Delia Derbyshire and the BBC Radiophonic Workshop definitely deserve some love in this list". (From Peter via email, thanks)

Next: Keith Emerson