87-89 Saffron Hill was the Head Office of Aircraft-Marine Products, Great Britain (known as AMP). They had factories in Port Glasgow (closed in 1999) and Bideford (later Tyco Electronics) which closed in 2013.
Photos on this
Grace's Guide web page suggests that the Saffron Hill office opened after 1958 and before 1961
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Bideford factory
SS4625 : Entrance to Tyco ElectronicsPort Glasgow factory
NS3373 : Disused Factory