Beck was an electrical draughtsman and produced drawings of electrical
circuits; circuits used in the running of the Underground itself
but his training had given him knowledge of the symbols and techniques
used to depict wiring, diodes, resistors, junctions and valves.
He obviously knew of the colour coding used on resistors and capacitors
and had the considerable draughting skills to produce concise
drawings ~ this was after all his job with London Underground,
and as he lived and worked in London he had experience of the
tube system itself. Familiarity with a design 'need'
a tremendous help when it comes to finding solutions to a problem
and Beck's home in the north London suburb of Finchley was far
enough away from the city that he would have frequently used the