The LMS did paint coaches in the maroon/gold stripes for use behind a similarly painted 'Duchess'. It was only one set and they were shipped to the US, along with Duchess of Hamilton, for a series of publicity runs. The plan was maroon/gold stripes coaches for the 1940 Coronation Scot.
The plan for the return of the train came to naught due to the intervention of a guy called Adolph Hitler! The loco was finally returned to the UK in 1943 although the coaches remained in the US untill the war ended