According to the Nationalrail site and Ceefax:

"Virgin West Coast, Thameslink, Chiltern Railways, Midland Mainline
and Central Trains will accept Silverlink County tickets where
appropriate."

So, can I buy a *Silverink only* First Open Single from Euston to
Birmingham New Street tomorrow morning at £39 (half the cost of the
Virgin FOS) and travel in First Class with Virgin (and get the
complimentary food/drink too)?

All I know fur sure is that Virgin are accepting Silverlink dedicated
tickets but it fails to mention if they are valid in the same class of
travel. Can anybody confirm?