All of these coaches are Era 4 models. Details of the periods covered by the era numbers can be found here.
After several trials British Railways selected a livery of crimson and cream for its' mainline passenger coaches and plain crimson for suburban and parcels coaches.
It takes a very long time to build and repaint a fleet of passenger coaches, offering a great variety of coach stock for modelling this time period. The new BR standard Mk.1 coaches were coming into service alongside the older pre-BR coaches, many still painted in their old company colours. Slowly the company colours disappear as until 1957, when BR changed to lined maroon for new repaints. Even then the crimson and cream livery was only slowly displaced.
Heritage railways and mainline tour train sets have ensured that crimson and cream liveried coaches have survived to be seen alongiside the newest trains in service today.