1st class for only certain legs

[Crithylum]

When using split tickets, it sometimes makes sense to only get 1st class for certain parts, (£5 for catering and lounge access is good, £15 to sit in the front first class instead of the rear isn't). Right now, the only way that I see of doing this is to set up seperate journeys. Another difficulty is that I have to search the price premium for each leg individually, as the forum only shows the price of upgrading the whole journey.

Is there any more efficient way to select 1st class for only certain legs?

 

[MrJeeves]

The forum's site will issue standard class tickets as part of splits if the trains you're on don't have first class, but you're right that there's no way to control this on a per-leg level if the trains do have first but it's not worth the extra cost.

I would love to have the option to "avoid first class" per-TOC; I might want to travel on Thameslink to connect into Avanti, for example, but I wouldn't want to pay for Thameslink 1st unless it worked out cheaper through an Advance.

I don't think anything supports functionality like this or like your suggestion at the moment, though. You'd have to do an end to end journey search, as well as searching for each part of the journey yourself to try and find the best deal, but you also might miss some splits this way!