I doubt FGW▸ (or GWR▸ ) would entertain running the train via a circuitous route when things back to normal.
Ah but normality with this train is the abnormality / changes to how the summer peak has been handled over the years
Edit to add - 5th September 2015. I rode on the final run of the year from Bristol via Bath this morning to provide some figures to compare. Not really fair to the regular route as it's no longer a peak weekend, and they had just the one service to market in this series against our 5 (became 4). Weather - overcast but pleasant.
09:06
BRI» to WEY, 8 car
HST▸ ex BRI 5 + 4 + 29 + 20 + 20 + 2 + 1 + 9 = 80
+20ish, -0 at Keynsham
+6 -3 at Oldfield Park
-55ish, +6 at Bath
ex
BTH» 4 + 5 + 4 + 15 + 10 + 2 + 6 + 13 = 59
-4 +4 at Bradford on Avon
No specific count at Trowbridge
ex
TRO» 3 + 5 + 5 + 16 + 16 + 8 + 7 + 12 = 72
initially -5 +4 @
WSB» then about 25 extra joined - ex London connection.
Train departed with between 95 and 100 passengers
Notes ... intermediate traffic BRI - BTH, but other trains just ahead and behind would have catered for that flow had it not run.
Only a handful of family groups
Strong on "rail interest" people - note numbers in declassed 1st (all above counts started at coach A).
Following (30 minutes or so) was a 4 car unit train (150/2 + 150/1)
10:29 (TRO time) BRI to WEY
4 cars, approx 100 passengers (counted 2 coaches; 35 + 20 + ? + ? TRO-WSB); not through corridor between units)