I came across a mine rescue team training on Roseberry today. An unreal sight, dressed in full PPE and carrying masks, helmets and oxygen packs, it must have been a very exhausting day for them. I assume this training in broad daylight is a preliminary exercise for kit familiarity.
They belong to Triton Mines Rescue which are seconded to the Anglo American Woodsmith fertiliser mine near Whitby.
Here is a BBC Look North video of the team conducting a simulation exercise in a former ironstone mine.