Ask the little old ladies in your local charity shops to look out for Whitney blankets, they'll understand what you are on about.
I paid £4 for a nearly new off orange colour one yesterday in a charity shop in Accrington. It was still in the original logo'ed plastic bag. There was a even nicer, bigger, thicker one but it was the brightest pink you've ever seen.
It was the manufacturers of Whitney who supplied the North American market and I can vouch on the quality.
I'm going to thin out my stash soon, swap some maybe. The dust from them when stored/ not aired/used regularly brings on my allergy. D'oh!
ATB
Tom