It's a shame they haven't utilised the passenger section better.
Part of the franchise commitment was to have scenic trains in a 'sperate premium carriage' with tablecloths and breakfast, lunch and dinner hampers. The franchise commitment also mentions special events such as keynote speakers giving talks, whisky and food tasting events etc. It also states there should be Premium comfort seating that maximises passenger comfort. I can't see how an ironing board could ever fit that bill!
I thought it would have made sense to have this new scenic section with comfy seats in the 153. That way it would be distinguished from the attached 156. It would also give the passengers, keynote speaker, food tasting expert, etc
more privacy without other passengers walking through, assuming the bike end of the 153 is attached to the 156.