Aston Martin Lagonda sedan spy shot

Aston Martin may be known more for its two-door GTs and cabrios, but it has made a handful of four-door sedans. They've historically worn the Lagonda name as either a nameplate or marque, and that's just what we seem to have here.

Spied running along familiar test routes in the UK, this prototype is reportedly registered to Aston Martin and based on the current Rapide S, complete with the company's long-serving AM11 6.0-liter V12. Only whereas the Rapide packs everything in tight on a short wheelbase – albeit with more room in the back than the two-door DB9 or Vanquish – this prototype appears to be riding on a stretched wheelbase.

Over that lengthened frame, Aston's Q customization department has apparently draped custom bodywork with lines that seem to blend elements of the last Aston Martin Lagonda sedan that wedged its way in between 1976 and 1990 on the one hand, and Zagato's pair of Centennial concepts presented last summer on the other. One thing it clearly is not, however, is the Lagonda crossover concept which Aston revealed to mixed reviews at the Geneva Motor Show back in 2009.

The big question is where this sedan is heading (beyond its test route). We could be looking at a highly exclusive creation for a handful of wealthy clients, or at a production model to relaunch the Lagonda brand as has long been anticipated. We're hoping it's the latter, but we'll just have to wait to find out. Judging by how close it looks to completion, it shouldn't be too long.