saw this coming up soon so will try and catch some photos
https://www.railwaytouring.net/uk-day-trips/the-bath-bristol-christmas-express
4th december empty coaches from southall to swanage
https://www.realtimetrains.co.uk/train/U10546/2019-12-04/detailed
5th swanage to bristol
https://www.realtimetrains.co.uk/train/U10547/2019-12-05/detailed
5th bristol to swanage
https://www.realtimetrains.co.uk/train/U10551/2019-12-05/detailed
5th empty coaches back to southall
https://www.realtimetrains.co.uk/train/U10553/2019-12-05/detailed
official website timings and rtt times slightly differ by a few minutes though
https://www.railwaytouring.net/uk-day-trips/the-bath-bristol-christmas-express
4th december empty coaches from southall to swanage
https://www.realtimetrains.co.uk/train/U10546/2019-12-04/detailed
5th swanage to bristol
https://www.realtimetrains.co.uk/train/U10547/2019-12-05/detailed
5th bristol to swanage
https://www.realtimetrains.co.uk/train/U10551/2019-12-05/detailed
5th empty coaches back to southall
https://www.realtimetrains.co.uk/train/U10553/2019-12-05/detailed
official website timings and rtt times slightly differ by a few minutes though