Thanks Ken,
Another good one
Not many keywords in its Aerofiles entry and Wiki has the Mooney 301 categorised under
United States civil utility aircraft 1950–1959 
, so I missed it on the first pass!!
The reason I didn't look further than the Beech Lighting at the time was what wiki said about the seemed to fit the clue well.
"Beechcraft originally planned to put the Lightning into production but the economic downturn among general aviation manufacturers in the United States in the 1980s led to the project being shelved"
I was going to bed, but seeing as I've still got a cockpit to monitor I will take Graeme's OH and put something up shortly.