Thanks all. And I had just taken the car in for MOT the previous afternoon. The garage kept it overnight for repairs, so I had to take the dog's corpse to the vet by taxi. Inevitably,with my luck, the Muslim cab driver asked what was in the bin liner. I didn't think it wise to say it was a dog, though not a live one! I told him it was dog food. When we got there, he'd obviously been thinking about this, but also had seen I had come from a farm. He asked "Is it a rabbit?" :) By then, I was out of the car, so didn't feel the need to reply !
She was about 13 but very active. I heard a cry from her, she appeared, looking ill, lay down for a bit, got up, walked to me and then died. I assume there was some form of heart attack involved. Though I have other dogs, including this one's dam, there is always a feeling of loss.