@NWL I think you are correct. Your comment about the "whistle in the cab" sent me scrambling for my Type XX locomotive (much the worse for wear than yours and without the leading truck) to see the resemblance. This one has the whistle in the cab and has a similar amount of trim on the boiler but lacks (maybe its just missing) the cylindrical headlight extension on the boiler front and as I mentioned it has no leading truck. Interestingly mine shows no evidence of ever having such a truck but who knows. There is no question that this type XX resembles your engine more than the one that came with my Champion outfit. My type XX shown below.
Best wishes
Don