I saw it too at Kettering, only thing I'd say is, that the builder should not be a reflection on the kit, anyone can make a hash of the best of kits, and some gifted people can make a gem out of a poor kit. Not sure on the cab roof profile but its clear to see it has not been formed to the same profile as the end sheet, the bonnet tops have also been poorly formed, overall the model looked like a rushed build (steps not straight, sandbox on the sqewiff and generally not put together that well IMHO) when compared to the Jinty next to it, agreed not good for a sales promotion as I'm sure it'll put a few off. Looking closely I think if the bonnet and cab roof was formed correctly and sat down on the body in the correct manner then it might resolve some visual issues.
Kindest