The cab roof not flush with the top of the short bonnet is an interesting 'error'. In photos that I have seen of the class in service the cab roof was flush, but there is a side-on photo of D8200 in the January 1958 RO and the cab roof is definitely not flush. The photo is credited to BTH so presumably taken before the loco entered traffic.
I wonder if modifications were made to the cab height before the loco was officially delivered to BR, but Heljan have sourced the original drawings which did not include the modification?
