It appears that the quoted fares are not "increases" but are the current higher-priced versions of advance fares. Presumably there is no quota for the cheaper advance fares on the dates queried.
I agree, but my point is that these fares have largely been at a stable level for the last 18 months that I've been doing this trip each week, excluding an occasional peak here and there. PAX numbers appear to have also remained fairly steady also, although this is largely based on occupancy in Coach G.
However, there seems to have been a huge jump in fare prices from mid-May onwards in both standard & first regardless of travel day, with the exception of some trains at increasingly inconvenient times - the specific example provided was as it is my usual travel days & time.
I fail to see that there has been a sudden rise in demand from mid-May onwards that is sustained evenly throughout the timetable as far out as the last week in June, so my (rhetorical in this forum) question is what has happened to the quota of the cheaper off-peak advance fares that has in the past been consistently available on my chosen trains for the last 18 months up to about a week before travel date? In effect it seems this is some kind of increase by 'stealth'.
I plan to pose this question to
FGW▸ , but was interested to poll opinion here in case anyone else had noted similar issues on other journeys.