It's a Vivastella 1931 [Type PG4 Luxe] bodied by Million-Guiet. This coach manufacturer from Levallois-Perret (Paris) had a plant in London too (Old Bond Street)
By the way, I confirm that pictures have bad ratio. The appropriate tend to 1,5 instead of the 1,79 (L/H).
For instance, these pics on Dodge WC, VW Sedan or Willys M170 should be: