The belt had come off in their washing machine. She was knelt behind it, with the back off, guiding the belt back on, while he turned the drum from the front. Heater element terminals are just below the drum pulley, and, for reasons I've never worked out, tend to be switched on the neutral side, so are both live whenever the machine is switched on.
She must have touched one of the terminals, and was found dead in a kneeling position behind the machine, when her partner realised she was not responding to him.
Rewiring, with new RCD protected consumer unit, was due to start in a couple of weeks time.