Aston Martin Works, the world-renowned heritage arm of British luxury sports car maker Aston Martin Lagonda, is promising visitors to the upcoming Retromobile Show in Paris next month an unprecedented view of one of the brand’s rarest and most sought-after classic cars – Aston Martin DB4 Convertible, chassis no. 1173. This one-off model, built in 1963 at the historic home of Aston Martin in Newport Pagnell – now center of operations for the Aston Martin Works heritage sales, service, and restoration business – is unique as, of the circa 70 DB4 Convertibles made by the brand between 1961 and 1963, chassis no 1173 is the only car known to have been built by David Brown’s factory team with the more potent DB4 GT engine as an original fitment.