...The Doctor Who theme music is a piece of music written by Australian composer Ron Grainer and realised by Delia Derbyshire at the BBC Radiophonic Workshop. Created in 1963, it was one of the first electronic music signature tunes for television.

Although numerous arrangements of the theme have been used on television, the main melody has remained the same. The theme was originally written and arranged in the key of E minor, utilising the phrygian mode.

The original 1963 recording of the Doctor Who theme music is widely regarded as a significant and innovative piece of electronic music, recorded well before the availability of commercial synthesisers.

Delia Derbyshire (assisted by Dick Mills) of the BBC Radiophonic Workshop used musique concrète techniques to realise a score written by composer Ron Grainer. Each note was individually created by cutting, splicing, speeding up and slowing down segments of analogue tape containing recordings of a single plucked string, white noise, and the simple harmonic waveforms of test-tone oscillators which were used for calibrating equipment and rooms, not creating music.

The main, pulsing bassline rhythm was created from a recording of a single plucked string, played over and over again in different patterns created by splicing copies of the sound, with different pitches and notes achieved by playing the sample in different speeds.

The swooping melody and lower bassline layer were created by manually adjusting the pitch of oscillator banks to a carefully timed pattern. The non-swooping parts of the melody were created by playing a keyboard attached to the oscillator banks. The rhythmic hissing sounds, "bubbles" and "clouds", were created by cutting tape recordings of filtered white noise.

Once each sound had been created, it was modified. Some sounds were created at all the required pitches direct from the oscillators, others had to be re-pitched later by adjusting the tape playback speed and re-recording the sound onto another tape player.

This process continued until every sound was available at all the required pitches. To create dynamics, the notes were re-recorded at slightly different levels. Each individual note was then trimmed to length by cutting the tape, and stuck together in the right order.

This was done for each "line" in the music – the main plucked bass, the bass slides (an organ-like tone emphasising the grace notes), the hisses, the swoops, the melody, a second melody line (a high organ-like tone used for emphasis), and the bubbles and clouds.

Most of these individual bits of tape making up lines of music, complete with edits every inch, still survive...