Been thinking about this recently, staying with 4mm not Trix or early Triang
The Triang Hornby ones were actually not too bad, the roofs were correct but the ends were not good.
Mainline had a good stab - they actually produced a corridor second! But the windows looke funny.
Lima - well a right mixed bag, they offered up the option of B4 bogies, but all had the roof of the corridor composite and chassis was as crude as Triangs offering. I think about half of mine are Lima or Lima based with etched sides.
The TSO and SK were again welcome. But they had holes (see later)
Now Mainline brought out the first high detail Mark 1s with the RBR, a lovely model. I manged to find some similar rubber gangways to detail most of my Lima fleet. My memory merges here with Replica. This was also the first RTR Commonwealth bogie.
All around this period there were quite a few etched sides, I shortened a Triang chassis for a BG, used the sides with a new chassis better suited to LNER. (Flying Scotsman coach), resided a Lima RBR as a RU and used a kt chassis with BCK sides.
There were some quite nice kits as well. Used them for parts too - Cooper Craft I think SK FK CK BCK and I think the FK was a first.
Now Replica had the Mainline moulds and we then got a good RTR BCK and the first scale length BG and then an Open First, all nice models looking so much better than the Lima stuff.
Now the market remains like this until Bachmann produce their models. They are similar to the Mainline Replica models but with flush glazing. They also have lots of bogie options, I own a few and have replaced the Commonwealths on a BG with B4s as almost all air braked BGs (NEAs) had B4 bogies.
Now all these different models can be scarey, but luckily the paints are all similar colours and super detailing helps Lima*.
- BR1 - 14mm wheels, close coupled, B4 rotate 180 deg and close couple. Fit better roof vents, fit rubber gangways found a lot in a box at a model shop and cleaned them out!! Also flush glaze.
The only odd lookers really are the original Mainline models.
It though is interesting to see how the market has changed from literally brake second corridor composite to about 10 types in RTR production. People may knock the Mark 1 but it has been on our railways now for over 50 years, and has had at a quick count about 20 basic designs not including prototypes, post office, and sleepers once (all same body)