Hardblood is a term used to describe a whippet with a good dose of greyhound blood Snelly. There's one that was winning a lot last year that I was trying to use on my black bitch and that was actually 7/8 greyhound but ran as a whippet as it could fit in the traps used for bends racing. Some of the whippet racing folk are dead against it, naturally, but others seem to like it. Basically, hardblood is an unregistered grew.
You're right about Phil, he was the one who nudged me in the direction of using that blood.