This etch represents the final form of these vehicles. After being in service as D2664 for about a year the coaches were rebuilt following severe complaints from diners. The fundamental change was the replacement of the high windows by conventional ones, allowing travellers to see out whilst dining. The seating was reduced from 24 to 18 firsts and from 40 to 36 thirds, laid out 2+1 in both saloons. The saloons were also changed over end for end. At the same time the brakes were changed from the Prestall system to conventional vacuum cylinders and V hangers, initially retaining the single large vacuum reserve cylinder. The original version to D2664 is available as Comet Models S11BS.
They ran in tandem with a Tavern Car to D2663 (Comet S11AS) or the rebuilt version to D2668 (Comet S14AS).