Hi, "Autotank", and welcome to the Forum.
How long an answer do you want
??
The management overiew is "it would probably make a lot of sense to provide an appropriate service on the Wallingford line, but there's an awful lot of other places that it would make similar sense to do something similar and it's not happened."
The longer answer involves availability of rolling stock, costs of raising track to very high standards legally required and other health and safety issues, ensuring that there's enough in it for commercial interests involved to get their profit for their shareholders, capital investment sources / underwriting by the local transport authority in the area, red tape, all the movers and shakers being too busy doing other things realting to meeting demand on lines already open, and on major projects such as Reading and Crossrail. On the positive side, if you have a rail-friendly local authority (
LTA▸ ) that doesn't have its thought all tied up in local government re-organsation, a helpful
MP▸ , a marginal constituency, and some development that could help with section 106 grants and the like, and you're in a depressed area that the
EU» will help fund, or if you have senior rail people living in the place(s) that would be served.
When I first got involved with railway campaigning, three people cautioned me against excessive optimism (which in fact I didn't have - but they weren't to know that) - and the words stick in my mind "Graham - a rail based campaign takes ten times as long as an ordinary one, and there's an extra zero on the end of the price too".
I'm not trying to put you off here ... but across the
FGW▸ territory, have a look at campaigns / comments with regard to Portishead, Okehampton, Tavistock, the TransWilts line, Radstock ... (and I have probably left out a few) but also Severn Beach, Ebbw Vale, Newquay and Maesteg where you'll see services running which previously were not.