Blue Motorized coach (Mighty Mac like)

I cannot identify this at all. I'd have thought it came from a short-lived TrackMaster set by HiT Toy Company if you hadn't told me it was marked Tomy, so that only makes it a Motor Road and Rail item. I know there have been some unusual releases and compilations in the range both in the US and UK but all I could think is that it's a factory error.