Greg confirms that she is, as I suspected a Morecombe Bay Prawner, the hull was moulded by Eric Berqvist, who also moulded the Memory which Greg later built at his Salterns yard and the diminutive Winkle Brigs. The moulds were taken from an old motor prawner "Sir William Priestly",
Apparently the mouldings were twisted in the counter so Greg undertook an extensive rebuild having purchased the stripped out the GRP hull and deck from the now long gone Classic Yachts Ltd at the Triangle Boatyard in Bittern. It needed some massive reinforcing with new bulkheads, frames and deck beams to prevent flexing.
Greg then fitted out Black Jack work boat style with an iroko coach roof and internal t&g interior.
Black Jack was fitted with "inherited" sails and spars but as a result was under canvassed, which combined with the shallow draft didn't sail that well.
All that took place about 30 years ago, she was sold to help pay for his studies at the local Warsash college. Black Jack has been since sailed extensively including the channel islands and a spell in Wales before coming back to the Solent and her current home in Keyhaven.