That is wholly incorrect.
Each "type" of device requires such an Order ("type" such as radar, cable sensors, light beam etc.) but specific devices within those types only require "type approval" by the Home Office.
S.20 of the Road Traffic Offenders Act 1988 originally allowed for radar devices; this section was amended by
S.23 of the Road Traffic Act 1991 which allowed for further Prescribed Devices (i.e. new types of device introduced by Order laid before Parliament) and all devices of the new types to be Type Approved.
The Road Traffic Offenders (Prescribed Devices) Order 1993 brought forth two more types of device, sensor/cable and light beam. Again specific models of each type only require Type Approval.