Links to Railway Sites
The following are links to the sites of preserved railways. I have visited them all, and recommend them all:
The Battlefield Line (Will literally take you to Bosworth battlefield if the service is running on your chosen day.)
Festiniog and Welsh Highland Railways
Gloucestershire Warwickshire Railway (This can easily be combined with a visit to Tewkesbury.)
Great Central Railway (Very close to Leicester and Richard III's tomb.)
North York Moors Railway (Very handy for York, Sheriff Hutton and Scarborough.)
Welshpool and Llanfair Light Railway