Thanks, it was a shock and here is a brain-dump of things about her.
We called her The Terminator, because she would just not give up. She had a tough upbringing, a failed breeding dam, then off to some friends who run a B&B. Cali loved sitting on people's shoulders, and stealing food. Not good for a B&B cat. She ate most things, broccoli, cake, biscuits, bread. She was a small cat, but she also had to be Top Cat, which as they already had two strong cat characters was never going to work out. So she got shipped back to the breeders, and we said we would take her. We got a kitten too, but Cali was not one to be motherly, far from it. She was aloof and damaged, and stared at you - as if sucking your soul out. That was 8 year ago, when she was 6. Last year the B&B friends asked us how "That Thing" was doing - it was great to be able to say that she was settled and happy. She mellowed as she realised this was her home and we liked her. Although she would eat anything, she had allergies from food. So she'd get scabby. Bloody patches that she relentlessly scratched. We largely solved that with hypoallergenic food, and she only lapsed into scabby-abbyness when she stole food.
A few years ago we ended up looking after a dog for a weekend. Friends had said they would look after her, but forgot they were away. The trouble with the dog was that she bullied cats relentlessly. We said that was no problem as our cats would make themselves scarce (as our friends cat had done - disappeared upstairs whilst Myrtle stayed). So, Myrtle arrives, and settles in the kitchen. I forget that the cats are supposed to be kept away from this cat-terroriser. There was an almighty howling and I went to the kitchen, where Myrtle was cowering in a corner. Cali just sat, staring at her, Terminator style.
Myrtle never bothered any cats again.
She loved men and company and was so characterful. We are all very sad. Although it was very quick, there was no time to say goodbye. Good for her, but sad for us.