This is one of a fleet of Packard sedans bought by the secret service (MI6) in June of 1940. They were sent to a coach builder in the Midlands where their coloured paintwork was replaced by camouflage. They were fitted with mobile radio transmitter to enable each vehicle to act as an independent mobile wireless station.
The cars were then dispatched to various war theaters where they acted as special communications units which served to pass on the top secret intelligence that had been extracted from cyphers and signals at Bletchley Park to military commanders in the field. The use of these special communicatiosn units ensured that the top secret intelligence was seen and handled only by MI6 staff and the commanders directing the war.
This example was repainted after the war.
Pete's Favourite Things 
Just seen the Packard from Bletchley Park.
I remember my grandfather (who was stationed there from 1943-1945) telling me that he used to drive such a car. He also commented how difficult it was to change a wheel during the blackout.