I also live in Leeds, and remember 2012 was quite disappointing, even though the rest of the country seemed to have a record year for storms! Last year did take a while to get going, but we had a spanish plume in late July after the heatwave, which brought an interesting thunderstorm, although, like you said, it was mainly obscured by fog. There was also a spectacular storm in early august, which whilst it didn't go over us, it produced some quite vivid heat lightning. October was an interesting month, with a possibly supercellular storm on the 25th, which brought some spectacular C-G's, and torrential rain. November saw a squall line on the 2nd, closing the storm season! This year has been very active south and west of the pennines, especially on the 22nd May, and 7th June, but these storms seem to have missed us. Fingers crossed for a more active summer!