Advance rail tickets

[gillhalfpint]

We have advance tickets for the 11.50 Virgin on Thursday from Birmingham New Street to Euston, and wondered if anyone on here knows what happens if that train is cancelled and they manage to get us on another one.

Will our advance tickets we bought when they came out for the journey that only cost us £6.25 each Birmingham to Chelmsford still be valid,if THEY make the change, or will we be expected to stump up whatever the single fare will be on the day, something like £30+ when I last checked.

Cheers.
Gill
P.S. Just found in terms and conditions that they can accomodate on another train if booked train cancelled but no guarantee of seats. That will do, just want to get there and on to Chelmsford as we are trying Podge's Belgian Christmas tour.