They are a twin set because the rebuilt observation carriage 100 was the first on the FR not to include a compartment for the guard and a vacuum brake setter. Instead this function is located in carriage 124, the first of the 'service carrs' which contains an area for the guard, a toilet, buffet store and preparation area and a diesel generator to provide an electric supply.
Because it has no guard accommodation 100 runs in formation with 124, which you can see here below.
They are being built according to my usual styrene technique and will be the 9th and 10th carriages produced at Boston Largs Works for Blaencwm Works, which you can read more about in this blog.
This client has also ordered a model of 'Carnforth' carriage 112 which will be the next one I'll work on.
(I didn't mention that until now because it's not a Barn design and spoilt the alliteration in the title!)
