I have been told, third hand. A toddler apparently has a habit of climbing into a washing machine and closing the door behind them.

I would have thought that this possibility would have been designed out by the manufacturer.

I will probably have a chance to witness this during the next week or so.

Potential dangers are obvious, especially with a slightly older sibling about.

I would advise the parents to change washing machines/Keep machine unplugged when not in use. I know that this in reality will not happen.

So, is there a sort of "one shot adaptor" that could be plugged in to the socket and the machine plugged into it. switch washer to on then nothing happens till a "one shot" button is pressed and it will de-latch.

I remember years ago, a plumbing wholesaler around here, sold "one shot switches" for immersion heaters. It needed the wiring split and another wire adding to the cylinder stat and this enabled a mains relay to hold in via the thermostat and once the cylinder heated up it caused a dropout  therefore the tank cylinder would heat up once only unless the button was pressed again. I do remember examining one and the relay coil was powered by the stat, a resistor and a capacitor in series I think. They seemed to work in actual practice and apparently were intended mostly for dual heater cylinders with the remaining heater & stat wired in the conventional way maybe on off peak supply.

Off course the washing machine situation would require such relay or whatever to hold in whilst some current drawing and latch out on nil current.