Notts CC have just bought various former colliery lines from NR, they are now looking into funding for works to turn them into walking/cycling(/horse?) trails.
Nothing very long, will be mostly local leisure trails rather than part of national cycle network I think.
IIRC much of BRB property is going to Highways agency, maybe also country councils, since it is often bridges & viaducts in highway corridor so will be easier for Highways to maintain (or flatten...?) them.
I hope none of it is lines which might be reopened at some point...
In this regard the cycle route approach does keep these alignments free & prevent them being built upon, much easier to divert a cycle route than demolish buildings....