Steam Dreams -
http://www.steamdreams.com/ - running from Banbury, Radley, Swindon, Chippenham and Melksham to Exeter St David's, Paignton and Kingswear. Provisional timing - 07:30 from Swindon, 08:00 from Chippenham, 08:15 from Melksham, arriving back 20:15 (Melksham), 20:25 (Chippenham) and 20:50 (Swindon).
Fares from £99 to Exeter, £109 to Paignton or Kingswear
Note
This trip will be diesel hauled between Banbury & the West Country in both directions.
and
YOUR LOCOMOTIVE: 34046 Braunton is a ‘Bulleid Light Pacific’ express passenger engine designed by Oliver Bulleid.
I've checked with Steam Dreams - current plans are Vintage Diesel to Westbury, with Braunton from there to Kingswear and back.