bringing your dog on train

Hi - We are moving back to London and in the past we would take trains out to do weekend countryside walks.
When we move back in July we will now be bringing a 60 pound lab and are curious as to whether we will be able to take him on train with us.
The National rail site seems to say that this could be possible, but it's not very clear , wondering if anyone has actually had the experience of taking a dog , or seeing others with one.
Caroline
 

I've seen all types of dogs on trains and have taken my dog on buses and the metro many times with no problem.

Hi Lola:

This is great news!  We thought we remembered seeing people with dogs on public transport, but were'nt sure!

Thanks!

Caroline & Brendan