Great Western Coffee Shop

From Journeycheck https://www.journeycheck.com/greatwesternrailway/
Cancellations to services between Plymouth and Totnes
Due to heavy rain flooding the railway between Plymouth and Totnes the line towards Exeter St David's is blocked.
Train services running through these stations may be cancelled, delayed or revised. Disruption is expected until 12:45 04/07.
Customer Advice
CrossCountry are conveying passengers between Plymouth and Bristol Temple Meads in both directions until further notice. Arrangements have been made for Great Western Railway rail tickets to be accepted for these journeys

Cross Country are able to run through flood waters when IET's are unable to!  ???

Well, not in fact - no XC services have run west of Exeter this morning, while several GW ones (both IETs and local trains) made it through earlier - at least on the Down line; the most recent one on the Up line is held at Plymouth. So the puzzle is: why does the announcement read like that?

I presume it was a case of getting acceptance if you were travelling on a GWR only ticket or an advance fare if a XC happened to be in the vicinity at the time of your journey?

For example the 09:30 XC service from Penzance to Newcastle terminated at Plymouth, but was then restarted with another unit from Exeter.  If you were going from Exeter to Taunton that would have been a handy train to be able to use on a GWR specific ticket.

But yes, to confirm this was a closure to all types of train in the up direction at Laira Junction, with the down line remaining open at caution.  Since then the up line has also reopened at caution but for GWR only, not XC.

I think XC HST sets were allowed to proceed once up line opened under caution, but not Voyagers

At one point XC HSTs were being allowed through at 50mph while Voyagers were restricted to just 3mph.