Corridor or non-corridor coaches on 1920s GWR tourist trains?

[Penrhos1920]

In 1921 and the following years the GWR ran a “through tourist service “ for various South Wales stations to Aberystwyth.  I’m interested in the Newport-Aberystwyth train which had a total journey time was around 6 hours.  I not seen any photos of the train.  Photos of a Merthyr-Aberystwyth train show the leading coach to be a F9 clerestory double slip and the rest are clerestories.

 

Would the rest of the coaches be corridor or non-corridor on a summer months only through tourist service?