I'm looking at advance tickets from Ely to "somewhere in Cornwall" - for the sake of argument and simplicity lets say Penzance, but the problem I'm about to describe occurs with multiple different destinations, so is not Penzance-specific. These are for a Saturday "sometime in August" - again, for the sake of argument I'll pick 19th August, but this applies to all other Saturdays in August (except the bank holiday weekend, where availability of advance tickets is "different"), so is not date-specific.
Generally speaking, there are advance tickets available every hour from Ely, connecting into the xx:06 from Paddington to Penzance. However, there is one hour of the day when this doesn't work as well: the 07:52 from Ely, connecting into the 10:06 from Paddington, does not have advances available - only the walk-up fare is offered. But, half an hour earlier, the 07:26 from Ely, with a much longer wait in London, before connecting into the same 10:06 from Paddington, does have advances.
Why is this? From memory, these tickets only come with a seat reservation for the Paddington to Cornwall leg, and no reservations at all for getting into London in the first place. If I ordered the 07:26 departure, and wasn't given a seat reservation for that train, is there anything stopping me using the 07:52 instead?
This problem seems specific to departing from Ely. If I instead search for departures from Cambridge, then there are advances available on the 08:17 from Cambridge (which I would have to use if I got the 07:52 from Ely), and I'm not offered the earlier 07:48 from Cambridge with the much longer wait in London.
Therefore an obvious workaround if I want to use the 07:52 from Ely is to buy a separate Ely-Cambridge ticket, followed by a Cambridge-Penzance advance. Indeed, for me personally, I have a season covering Ely-Cambridge so will effectively be doing exactly this, but others that I will be travelling with do not have the season ticket, which is why I noticed the discrepancy. I'm happy with using that workaround for everyone else, but am more intrigued as to why this glitch with the 07:52/08:17 from Ely/Cambridge exists, and what the rules are for using a different connecting train to the one booked (assuming no seat reservations are given, of course)?
Generally speaking, there are advance tickets available every hour from Ely, connecting into the xx:06 from Paddington to Penzance. However, there is one hour of the day when this doesn't work as well: the 07:52 from Ely, connecting into the 10:06 from Paddington, does not have advances available - only the walk-up fare is offered. But, half an hour earlier, the 07:26 from Ely, with a much longer wait in London, before connecting into the same 10:06 from Paddington, does have advances.
Why is this? From memory, these tickets only come with a seat reservation for the Paddington to Cornwall leg, and no reservations at all for getting into London in the first place. If I ordered the 07:26 departure, and wasn't given a seat reservation for that train, is there anything stopping me using the 07:52 instead?
This problem seems specific to departing from Ely. If I instead search for departures from Cambridge, then there are advances available on the 08:17 from Cambridge (which I would have to use if I got the 07:52 from Ely), and I'm not offered the earlier 07:48 from Cambridge with the much longer wait in London.
Therefore an obvious workaround if I want to use the 07:52 from Ely is to buy a separate Ely-Cambridge ticket, followed by a Cambridge-Penzance advance. Indeed, for me personally, I have a season covering Ely-Cambridge so will effectively be doing exactly this, but others that I will be travelling with do not have the season ticket, which is why I noticed the discrepancy. I'm happy with using that workaround for everyone else, but am more intrigued as to why this glitch with the 07:52/08:17 from Ely/Cambridge exists, and what the rules are for using a different connecting train to the one booked (assuming no seat reservations are given, of course)?