About six when I was looking in the 80's. More than once I arrived to view a car to be told it had sold whilst I was on my journey. There was certainly no looking-then-go-away-to-think-about-it.
It will be interesting to see how things pan out. There's a dealer near me offering a really low mileage seventies plus 8 with 4 speed and the lovely narrow rear arches for 27k. Seems really cheap to me. He told me prices on all his lovely selection of impeccable classics had "stabilised". Presumably motor trader talk meaning "plummeted"....