This is of particular interest to modellers. Those who have had many birthdays fewer than myself and some other posters here (yiz know who ye are!) will be aware that prior to 1970, and the introduction of the NIR Enterprise and 80 class railcars a few years later, the uniformity seen almost universally since was almost unknown. Now, a modeller who likes Mk 3's will run them, with a EGV of the sole type they had. Craven-likers will run a train all of those, as will modellers of NIR Mk 2s etc.
So - if you like laminates, by all means; but back in the day you would almost never get a train of a uniform design of them, or of anything. Thus, models based prior to the early 70s almost need, as obligatory, a hotch-potch of all manner of stuff behind them.
In the colour pic at Manulla Junction above, we have (from behind the loco onwards), a GSWR wooden side corridor comp in green, a GSWR side corridor third in black'n'tan, a laminate in b'n't, a green laminate, what I think may be a Bredin in b'n't, and two other vehicles, whose side profiles show that they are different from each other, and from the others in the train. Thus, we have a seven vehicle train in two liveries and with no two carriages the same. A dirty silver luggage van, or an-ex-GNR KJ15 in blue and cream would equally have been possible candidates for inclusion.
Such a combination was typical, if not normal; and a train of uniform type was almost unknown. The opposite of today.