Nick Simpson thinks this is either a 3 1/2 Litre or a 4.3. Its a Vanden Plas Pillarless saloon. The unusual features that may help with further identification are twin air vents on the back edges of the bonnet top panels and it has twin spare wheels.
My guess is its a late 3.5 litre or early 4.3 Litre. Early versions had the front wings curved tight behind the front wheels – this has the later style wings. 4.3’s from chassis about 13177 had the spare wheel mounted in a can on the boot lid.
What do you think?