Harry Potter train run

[Judy Tait]

At some point, I remember seeing something posted about the train used 
in the Harry Potter movies doing runs for which you could purchase 
tickets and ride on.  But, I cannot remember anything about this now or 
any information concerning this, including any website one can go to 
and get schedule and purchase information.  

My husband and I -- who live in Scotland -- are discussing plans for 
doing a holiday later this summer, and I expressed the desire to go on 
this train run as part of our holiday, if possible.  Is there anyone 
here who can point me to the website -- or any websites -- with 
information about when this train does its runs, how to purchase 
tickets for it, where to catch the train, etc.?  Also, we will have our 
dog with us and want to find out if dogs (other than guide dogs) are 
allowed on this train -- does anyone know what the policy is about 
this?  

Any help I can get would be *greatly* appreciated -- thank you.

Judy Tait
Glasgow, Scotland