That train looks more like a multiple unit - I wonder why.
Because it's the first purpose-built driving trailer with passenger accomodation for locomotive powered trains in this country.
Operating loco-hauled trains as effectively MUs has been going on for a long time. The Southern Railway especially allocated most of its coaching stock into sets of two to eight coaches that could be combined into full trains, with a pool of loose coaches to strengthen them-
excellent posts can be found here. That practice was later revived with the southern region TC units- converted from "loose" stock but now with driving cabs at the end, looking (funnily enough) just like the EMUs that they worked with.
The Edinburgh-Glasgow 47 operated sets used converted passenger vehicles (Mark 2 Brake Standard Opens- if there had been more than three Mark 3 BFO or new build had been allowed then I'm sure that's what they would have used instead) so obviously still looked like "traditional" coaching stock, but were working as mainly fixed formations.
That continued with the west coast mark 3 DVT set, but this time the driving cars were specially built and looked much more like locomotives, helped by not carrying passengers. That continued with the Mark 4 sets, designed as a whole but with a DVT that was deliberately designed to look like a Class 91. These definitely operate in fixed formations unless there are technical issues.
And here we've got a passenger carrying driving trailer, of a design not unrelated to a new range of EMUs and DMUs that will be operating in the same area. So of course it looks like an MU