I really can recommend the Buckinghamshire Railway Centre as a great day out for all the family. There is so much there that it will keep you busy all day. I enjoyed my visit and would like to go back. On the day that we visited the centre there was also a meeting of one of the Jaguar car clubs. You can see from the photograph that there were some beautifully restored examples.
The address of the Buckinghamshire Railway Centre is http://bucksrailcentre.org/
I have also included two photographs of a Jaguar.