From the blog "Sixties Snapshots - 00 scale"

The ex GWR ‘B’ Set Airfix model coaches date from 1975. Almost forty years later and the coaches reappeared as Hornby R4293. The coaches must have proved popular and in the intervening years similar models have been available first from Mainline and later Dapol. Bachmann 9017 on Airfix ‘B’ Set passing Hornby Crimson ‘B’ Set The ‘B’ Set coaches were operated in pairs. As fitted with standard Airfix (or Hornby) couplings the gap between the coaches is hugely too large. Original Airfix/Hornb