I have found it very complex indeed to work out "who is who" with regards to decisions on the provision of an appropriate train service on the TransWilts line. As of mid October 2007, here is a summary of the key players in the jigsaw.  This list is written to the best of my availability / in limited time - so is errors and omissions excepted. 

The Major Decision Makers

* Department for Transport
Specify franchises, sign off rolling stock leases, etc
Ruth Kelly - Secretary of State for Transport
Tom Harris - Government Minister in charge of Rail
Mike Mitchell - Director General of Railways
Peter West - Civil servant who looks after FGW Franchise
David Hibbs - Civil servant, community Rail
Andrew Nock - Civil servant with close involvement
Brian Walsh - Civil servant with close involvement

* First (Great Western)
Train Operating Company
Moir Lockhead - Managing Director, First Group
Andrew Haines - Chief Operating Officer, First Great Western
Tom Stables - Commercial Director, First Great Western
John Curley - Route Director West, First Great Western
Andrew Griffiths - Region Manager, Severn and Solent, First Great Western

* Wilts County Council
Transport Authority for Wiltshire.
Judy Seager - Chair of Council
Fleur de Rhe-Philipe - Cabinet Member in charge of travel, transport, tourism
Keith Robinson - Chief Executive, Wilts County Council
George Batten - Director of Environmental Services
Allan Creedy - Transport section
Eric Egar - Transport section
David Philips - Transport section

And who else can wield a lot of influence?

* Members of Parliament representing stations on the immediate line
Ann Snelgrove - Labour, Swindon South
Andrew Murrison - Conservative, Westbury [inc Trowbridge and Warminster]
Robert Key - Conservative, Salisbury
James Gray - Conservative, North Wilts [inc Chippenham]
Michael Ancram - Conservative, Devizes [inc Melksham]

* Government's Ambassador for South West
Ben Bradshaw - MP for Exeter

* MPs with linked services
Michael Wills - Labour, Swindon North
Don Foster - Liberal Democrat, Bath
David Heath - Liberal Democrat, Somerton and Frome
Sandra Gidley - Liberal Democrat, Romsey

* Shadow Cabinet and other spokesmen
Theresa Villiers  - MP for Chipping Barnet, Transport Shadow

* Parliamentary Transport Sub-committee
Gwynth Dunwoody (MP for Crewe)

* Network Rail
Dave Ward - Route Director West

* Passenger Focus
Mike Greedy

* Others at First Great Western
Glenda Lamont - Customer Service Director
Lesley Coleman - Customer Panel
Peter Jobson - Area manager, Westbury

* Parliamentary Candidates for the new Chippenham marginal
Wilfred Emmanuel-Jones - Conservative
Duncan Hames - Liberal Democrat
Nick Thomas-Symonds - Labour

* Government Office South West
Peter Dawson
Richard Bayly

* Severnside Community Rail Partnership
Keith Walton

* Other organisations with influence may include ...
First Great Western Customer Panel
South West Regional Assembly
Swindon Council
Office of Rail Regulator
District Councils
Regional Developement Authority
Town and Parish Councils
ROSCOs
Trades Unions

Campaign and special interest Groups

* Campaign for Transport (ex Transport 2000)
David Redgewell
Cat Hobbs

* Travel Watch South West
Chris Irwin (Chair)
Gordon Edwards (Secretary)

* RailFuture
Nigel Bray - Chair, Severnside Branch

* Melksham Rail Development Group
Peter Blackburn (Chair)
John Hamley (Secretary)

* West Wilts Rail Users Group
John Ingram (Chair)
Sion Bretton

* CANBER (Campaign against new Beeching Report)
Lee Fletcher

* Save the Train
Graham Ellis

Influential Individuals not otherwise mentioned

Christian Woolmar
Barry Doe

Some Notes

a) This listing is written specifically to cover the "Savethetrain" campaign for a TransWilts service.  Most of the people involved have a wider role that just this one service, so much of the information is good for others too.

b) The "Campaign and special interest groups" section lists organisations and people who are - just like myself - campaigning for improvements. They are almost without exception very helpful, but doing the campaigning in their spare time and they are not the decision makers in any way.

c) You'll see I have not published contact details for the above people as I don't want this page to become a source of spam for them.  You can find out much more about most of them by doing a google search, and for most organisations you'll find they have emails taht conform to a pattern such as:
forename.surname@firstgroup.com
forename,surname@dft.gsi.gov.uk
forenamesurname@wiltshire.gov.uk