The Quicktest QT1 is a device made by Cliff which allows a quick and safe way to temporarily connect a mains lead to an electrical supply.
This video shows the UK single phase version, which has blue, brown and green connectors. A three phase version is also available, as is one with North American colour coding.
Althogh useful, this device is only intended for temporary connection in a testing environment and is NOT a substitute for a permanently fitted plug or hard wiring..