I wondered if that was a Scimitar Mike, the curve of the rear side window was the clue, but I'd not noticed the two-tone (which is just visible if you enlarge it
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Regarding axle weights, nowadays it appears to be appropriate tyres that limit their capacity. The axles on my 3500kg gross transporter look like they could carry a truck (massively thick square tube) but each one is rated at 1800kg due to the 8-ply tyres taking 900kg each. Hence being twin axle (4 x 900kg giving 3600kg limit) they are always working below their maximum rated capacity....