The whole operation is a bit of a shambles. Nothing like the EWS locos that ran 15 years ago. The security staff do their best to make it an unpleasant experience. They won't even let people take photos at Rhymney. Search for Rhymney on Twitter.
A friend of mine travelled down a couple of months ago for a ride behind 37421 - probably around September(?). I had mentioned the security staff guarding the windows before he went, although I havn't been down myself but have heard the stories. As many enthusiasts have done on the service he stood by a slightly open window (no more than 3inches open!) on the first door behind the loco for the music throughout the journey and had a rude security woman taking the p*ss out of him for the entire length of the journey and telling him he was breaching health and safety by having the window slightly open!
I travelled the Cumbrian coast behind the DRS 37s operated by Northern a number of times, windows fully open mid December for the acoustics and obviously couldn't hang out due to the prison bars over the window. Thoroughly pleasant conductors onboard every time, no issues or snotty comments and clearly used to the enthusiasts onboard - every window was lined with enthusiasts on each occasion I went. I moved away from the doors when people were boarding/alighting, helped open doors for those who couldnt work out the "complex" handles, and helped lift a couple of suitcases up the step when people were struggling. I was planning a nip down to Cardiff for the TfW set, but given the cost of getting there from my end and the amount of negatives i've heard about the onboard security I decided not to bother. Shame really!