A much more up-to-date overview of fares regulation:
www.parliament.uk/briefing-papers/sn01904.pdfOn
FGW▸ , where a Super Off Peak Return exists this is the regulated fare for that flow. otherwise it's the Off Peak Return.
If there is no Super Off Peak Return or Off Peak Return on a flow then the Anytime Return or Anytime Day Return is the regulated fare.
A full list of regulated fares flows can be found in at
this location. These are files I've uploaded to the cloud from a
Freedom of Information request. The list is in four parts. The fifth and sixth parts are the index to the ticket type codes used in the list and the index to the route codes used. Unfortunately the lists aren't in truly alphabetical order, so some manual searching is required to find particular flows.
Where a flow is not listed this will be because the origin and/or destination is part of a fares cluster and the main, or a nearby, station in that cluster will determine the regulated fare for the flow. For example, flows from Melksham may be listed under Chippenham. You can find fares clusters by using
brfares.com, entering the origin and destination and then selecting 'Expert Mode'. Look at larger neighbouring stations in the uploaded lists, or the first station named in the cluster. Not a perfect way of searching to find regulated fares for a particular flow, some trial and error is needed. Comparing the fares between actual origin/destination and the main location in a cluster is helpful. If the fare is the same then whether or not it is a regulated fare will also be the same.
For example, Melksham to York has the same fares as Chippenham to York. Finding Chippenham to York in the lists shows that the regulated fares are the Super Off Peak Return for the
✠Any Permitted routeing and the Off Peak Return for the
Not London routeing.
Link to Regulated Fares Flows list:
http://sdrv.ms/1gjJKkS