It may have been a Littleport-built Marvin from the Jim Burns Actualisers era (circa 1981).
The white-finished models (they also did black, in keeping with the Strat Hank was using at the time) had plain black scratchplates with no engraving other than the embossed Burns logo and in-house pickups made by a colleague there called Feinstein. The pickups were encapsulated in resin, with no separate covers and had adjustable hex-screw polepieces. The scratchplate was arranged in four separate pieces (the parts containing the pickups was separate from the part containing the controls).
The biggest difference was the use of a MIJ Strat copy bridge adapted for use with a small brass insert which provided the knife-edge bearing.
Most of them were made with applied maple fretboards, though there were some made with rosewood and a few with ebony fretboards.
http://blackguitars.com/IMAGES/gallery/burns-early-reference/1982%20Jim%20Burns/burns-sheet-2.jpghttp://blackguitars.com/IMAGES/gallery/burns-early-reference/JB-trade-fair-3.jpghttp://blackguitars.com/IMAGES/gallery/burns-early-reference/1981-Burns-Marvin-810182/1.JPG