I have read it, and stand corrected. Given, however, that a First
Class ODTC is a TOC-specific (Thameslink) product - I think it's only
them - I'm not sure how it applies to that.

In what sense is it TOC-specific? Day Travelcards from Cambridge to KX
aren't TOC-specific.


The Thameslink First Class one-day travelcard (I don't know if it is still
available)
used to be valid on Thameslink only (i.e. not Midland Mainline).
It was the same price as the standard class ODTC, which was valid on any
train.

Thameslink first class isn't really worth the bother, even for no extra
fare,
and you were unable to use the faster trains.

--
Peter