Arises from ongoing research with my collaborators on development of electric and magnetic sensors. The combination of a unidirectional electric field sensor and a dipolar magnetometer allows information about the direction of a source to be obtained. The magnetometry aspects were undertaken by myself and RJ Prance. CJ Harland contributed expertise on electric field sensors. This paper represents part of the output from our RCUK Basic Technology programme (GR/R87550/01) which enabled us to attract a further EPSRC translation grant (EP/E042864/1) with letters of support including from the National Physical Laboratory (Dr. M. Hall, michael.hall@npl.co.uk).