Filling with water when off - not valve or backfill?

My Indesit WA111 starts filling with water as soon as I close the door. I can hear a chugging noise from the inlet valve and can see the water coming in through the powder tray. The water is clean.

Problem started happening without warning.

Turning off the water supply stops the water filling, although the chugging noise is still present.

Nothing happens if I turn off the mains power before closing the door.

I've replaced the inlet valve with a new one and the problem remains unchanged.

Note that the problem happens regardless of the settings on the front panel. No lights come on and the machine starts filling with water straight away. Gushes - not a trickle.

Any ideas?

Andy