And, an interesting name, as they were maroon initially, the UTA green (most green from new), then maroon with NIR!
But always, it seems, so badly weathered they LOOKED brown with brake dust all over them!
It seems that they were never brown!
They are suitable not only for ex-NCC lines right into the 70s, a common sight tagged onto railcar sets, but also on the GNR section between 1958 (UTA division) and 1965, but occasionally behind railcars to Portadown after that. They were usually on the back of passenger trains, rather than being in goods trains, but would have made occasional appearances thus.
Appearances on the Derry Road were possible but rare and short lived. I'm unaware of any heading south at any time.
There are quite a few knocking about at both Whitehead (where there is a beautifully restored one) and Downpatrick - of both types.