Hello,
A few photos of Webley oil cans with the pre-war 'Valvespout' can as depicted on the lid of your box pictured next to the collage and the immediate post-war can next to that. The 'Valvespout' can is by far the rarest in the UK with the 'Reversible Spout' pictured as the background to the collage being the hardest of the post-war cans to find in my experience anyway.
As you are already aware, Webley were notoriously slow in updating the images on their catalogues and boxes, so the box would most likely have been produced later than the picture of the oil can on the lid.
Happy Christmas
Brian