it's from the mid 80s, one of County's first designs after the business was restarted after the original County Sports went bust.
it was the predecessor to the Reflex; both had an internal blind hole drilled down through the blade from the splice.
This was apparently inspired by baseball. At the time there were a lot of US air force bases near Huntingdon and the service men came to HCB to have their baseball bats modified
The turbo was reputedly used by an England captain in the mid 80's, although with another maker's stickers on the bat for contractual reasons.