The SECR wainwright saloon of 1903 ran with three conversions of older first class coaches, and was a bogie coach 50’ long with two lavatories, three saloon compartments, and a coupe. It was intended for day use only. Other later saloons were added, but it only saw use for journeys in the SR area, such as to link with Continental trips, Cowes, or race meetings. If night accommodation was needed, the LMS train would then be needed. What little bit I saw of such workings you could get royals sleeping overnight in a secluded siding, to emerge bright eyed and bushy tailed at some venue first thing next morning, and this practice still occurs.
One peculiarity was that this saloon was numbered 1R, and the SR numbered it 7930. However, it was called the English Royal, as another 1R existed, a 54’ 12 wheeler, which had lavatories, saloon, bedrooms, and compartments, built by the MSLR in 1883. This was stabled at Calais, for Edwards little trips abroad (say no more, nudge nudge, wink wink) and this was the Continental Royal. The SR numbered it 7931, but it wasn’t repainted, and was sold in France in 1927.