Red Sprites seem to be related to high energy lightning storms, while not an Astronomical phenomena being at .c. 90km they are a very challenging phenomena to image. ESO have just published a video about sprites showing some imaged from Paranel & La Scilla in Chile see http://www.eso.org/public/videos/esocast81a/?lang as well as an explanation of what is known. Well worth watching.
I think UKMon or one of the other Meteor networks may have captured an image or two so they can be seen from the UK in the right conditions.
Regards
John