State of the Art Locomotion

I risked my life taking this, as these two beauties came thundering down towards me, belching steam and smuts. They are just outside Big Pit at Blaenavon, where there is a short stretch of the Blaenavon and Pontypool Railway that is operated by enthusiasts at weekends in the summer. However, I don't think these two locos are part of it. I don't think they've been anywhere for a long time.