The early car in the photographs and the much later car with the tanks in the front wings are indeed visually similar in the hood and side windows.
The earlier car may well be ELX 855, the second Two-Litre Drophead and the first LH drive example. The first Drophead, L852, was recorded in the Factory Ledger as an experimental car.
Although ELX 855 was first registered early in 1949 the saloons in that section of the Factory Ledger were all mid 1948. This could explain the windscreen treatment on the car in the photographs, which was also used on the earliest Saloons.
Interestingly, some Dropheads, including the first two, were recorded in the Factory Ledger as 'Drophead Coupe', whereas others were simply 'Drophead'. Purely conjecture on my part, but could use of the term 'Coupe' be identifying the 'Cabriolet' style cars?
John