Astir 8,
A very interesting observation re the front mudguard. I don't think it is an optical illusion.
I have used the larger .tif file that I was originally sent to try and check rather than the .jpg that I posted. Assuming that the stencilling on the side of the vehicle is straight, extending a line from that towards the mudguards does indicate that the front is lower than the rear.
I have now emailed the Crossley site and await a reply. As you mention, it is prossible that they supplied just a chassis so might not be able to help.