Hard white plastic plug with unsleeved pins.
The rear cover only has the word 'FUSED'. Sides have recessed areas to improve grip.
Cord grip is a flat bar, the screws have corroded due to being in a damp environment.
The pins are unsleeved.
Nettle items are no longer made - this example is probably from the 1970s. Nettle merged with Delta (later MEM) in the early 1980s.