That's right, but my point was a bit more of the moment than that.
Tradionally a CS mk3 was either all First Class or all Standard with the obvious exception of the First Class coach with the accessible dual occupancy cabin at one end. Then for a few months we had consistent composites, every coach was around 2/3 First and 1/3 Standard, with the same room numbers corresponding to the same cabin setups.
From how the coach plans have been described to me it seems that things are a lot more mixed up now between single and two bed cabins, and presumably to mirror the configuration of the new trains. So if a coach finds itself out of original formation then it's very likely that a First Class booking could land up in a Standard cabin.