The Rapido announcement on the company's website starts: 'Following the exclusive APT-E trainset and Stirling Single locomotive, Rapido Trains Inc. and Locomotion Models are excited to reveal a new partnership to produce the ground-breaking Prototype HST (HST-E) Power Cars in 4mm scale/OO gauge as part of the ‘National Collection in Miniature’ series' (my emphasis). I would agree, however, that it would make more sense and be quite likely that there would be at least some intermediate trailers produced. Fortunately, for those wishing to convert these coaches to represent Irish MkIIIs, the vehicles used on the prototype HSDT were fitted with buffers. But, as RedRich says, the resulting conversion would again be just a repaint of an expensive BR MkIII with wrong doors etc and, as Glenderg points out, the cost of a correct version would likely be prohibitive.