Gathering storm

A day away from the office, on a course in Stevenage. Bright, blue skies this morning if a bit blustery. Then on the way back, this is what the skies suddenly looked like between Ely and Attleborough about half-two ish. I was expecting a spectacular storm but nothing happened. But then again I could have missed the action, as I was on the train and the skies continued to be pretty spectacular for about another 20 minutes.