Electronic Music No.7 by William Lennox was completed in 1972 and marks the end of the composers first stage at the Utrecht Studios for Electronic Music.

Extracts from Electronic Music No.7 were given their first broadcast during an interview for Radio London in 1977, and was given its first concert rendering at the Institute of Contemporary Arts (ICA) in London in the same year,

An earlier performance of the piece by WDR in Koln was to have taken place in 1972, at the request of Herbert Eimert.

It is during the composition of this piece that the concepts later incorporated in Metaphysica Empirica appeared to the composer.

Electronic Music No.7 could be subtitled proto-Metaphysica Empirica, it consists of an effervescent introduction of some 6 minutes leading directly to the main composition of 31 minutes duration. The beginning of this composition is amongst the most powerful the composers has produced and for the period probably represented the most complex sound created in terms of spatial structure, density and range of components. The processes involved were developed in Electronic Music No.14 .