I am looking to do a Thames branch line rover and was wandering if I paid the 5 pound first class upgrade on one of the trains would it let me go first class for the rest of the day or just that particular train? It would be on a Saturday.
I'm the poster to which Yorkie correctly recalls as having a dispute with FGW over this, back in August 2012 (Can't believe it's been that long Yorkie)
Myself and four friends had set out on a day trip round Cornwall armed each with a Ride Cornwall Day Ranger.
As it was the height of summer, and in noticing that FGWs webpage said "Journey within one zone will be £5, two zones £10, three zones £15, four and five zones £20." in relation to first class upgrades, we all decided it was worth £5 to get first class access on all the trains on which we'd be travelling.
We boarded the 10:05 St Erth to Par service and sat in First Class, the Train Manager came round shortly after departure, and I explained what we intended to do, and asked whether the first class upgrade would be suitable, she advised me it was perfectly fine and she was happy to sell the tickets from Penzance to Liskeard as those where the extreme edges of the zone.
At Par we changed onto a HST towards Newquay, all was fine and a pleasant quiet trip ensued.
We briefly left the train at Newquay to stretch our legs but re-boarded to head back to Par. Now the Train Manager came round on departure, checked all our tickets (again he'd already done it heading to Par) and headed on his way. a short time had passed and he asked to see our tickets again, I showed him mine and he said I needed to pay again for the upgrade. I explained what I'd be told by the TM on the earlier service, to be told she was wrong.
The discussion went back and forth, and I remained insistent that my journey was Par - Par via several places (I'll come back to this later). In the end three of my friends bought new upgrades, myself and the other had our names and addresses written on the back of an envelope and he headed off after telling us we'd be put off the train at Par.
On the other HST services we used that day after this, not one Train Manager had a problem with what we where doing, and all seemed to think it was within the rules. The booking office at Par also said we where valid as long as we didn't pass Liskeard.
I sent an email to First Great Western shortly after the event, explaining in detail what had happened. The response was that I didn't have a valid ticket for first class as I couldn't possibly be doing a journey Par to Par as I'd explained.
I sent an email back containing scanned copies of the seat reservations I held in standard class for each of the trains I traveled on where it was possible to make a reservation.
A long time passed before I received an email advising me in light of the evidence of my intended journey they felt given the wording on the website at the time that I had indeed traveled within the rules. Though advised me that would be changed.
Two years on the website wording has changed, and therefore I wouldn't advise even with reservations that you attempt this.
On a side note my friend made a Subject Access Request to FGW asking for any personal information they held on him, it came back with no information, we wonder to this day what happened to the envelope with our details on. FGW denied that any member of staff would take details in this manner.
I'm not aware of any First Class Weekend Upgrade which allows travel on any but the train it was purchased on.
Possibly apart from the Gold Card one, which used to be applicable for the day (if you could get a guard who knew that!) , though with the changes to Gold Card benefits I am not sure that still exists.
I'm aware of several, I believe your assumption that it is only valid on the train which it is purchased is incorrect.
Virgin, TPE, and FGW allow you to use one upgrade if you need to change trains on your journey. And I have done so on all three operators.