the looe branch is self contained, why not run a heritage dmu on it?
There's a limited number of branches where it would be nice to run heritage units (even MORE heritage, Chris!) - not only to release stock but also to boost passenger numbes ...
let me see:Liskeard to Looe
Brockenhurst to Lymington
St Erth to St Ives
Slough to Windsor
Twyford to Henley on Thames
in addition to those where they're used already:Pier Head to Shanklin
Princes Risborough to Aylebury
Queen Street to Bute Road
However ... there's an issue with heritage stock - it's old, it's hard to maintain, and it might not be as reliable as a public service and businesses in the area require.
We only have to see the problems Arriva Trains Wales have with their class 121 to see the diffculties in keeping heritage units in regular service