All FR enthusiasts probably have their own mental associations with certain items of rolling stock.
For me this semi-open bug box - or Birmingham knifeboard Observation Carr, to give it a more formal title - always brings to mind the 1930's and images of Tan y Bwlch and Bessie Jones in Welsh costume.
The real carriage is a replica which was completed in 1997 and makes use of some of the original components from carriage number 2 (or 6, if you prefer) which was re-rebuilt into a closed First Class carriage.
This model was built from a Chris Veitch kit and shows number 1 as it ran when first restored to traffic in a two tone green and ivory livery.
The actual carriage has subsequently been repainted into what I consider the rather drab 1930's colour scheme of solid green sides with red ends.