Try to find the spot where the photographer was standing.
Looks like a Daimler DB 18 Super Sport 1948 -
gosfordclassiccars.com.au/vehicle/daimler-db-18-super-spo... This vehicle is more like red above cream perhaps.
https://www.flickr.com/photos/blue_mountains_library_-_local_studies Thanks that does look to be a good match.
" ... In 1939, Winston Churchill commissioned Carlton Carriage Co to build a drophead coupe on a DB18 chassis, chassis No.49531. He used it during election campaigns in the later 1940s. "
From - en.wikipedia.org/wiki/Daimler_Consort
Probably why Winston lost when he did !