In England, the use of electronic equipment for monitoring of structural movement in buildings was developed over a five-year period of work at St. Paul's Cathedral and Chichester Cathedral. The authors of this article recount the structural movement of St. Paul's over the years and the various techniques applied to monitor that movement. Electronic monitoring was begun in 1978. Potter and Gaunt explain the principles of electronic monitoring, and discuss the refined microprocessor-controlled system installed in St. Paul's in 1982 and the system developed for Chichester Cathedral.