|WJD class Tanker wagons|
The image above shows a brand new Mobil tanker in 1969. I believe it to be WJD501 or 502 but no wagon number is painted on the side of the wagon and it could just be WJE506 as they are almost identical in appearance. Battye library 331740PD.
Mobil owned WJD 501, 502 were built in 1969 to carry petrol and distillate. They were sold to BP in 1985.