The dramatic weather events are caused by La Nina (sorry, don't know how to get a "tilde" over the second n in Nina, you will just have to imagine the squiggle!)
For reasons not entirely understood, temperature fluctuations in the Pacific called El Nino and La Nina affect the climate all over the world. For an explanation that is just about comprehensible (well, to me anyway, you lot might be cleverer!) have a look at the relevant pages on Wikipedia.
And although we have had two winters with nasty cold spells, particularly in the north, those of us with long memories will remember the winters of the 60s and 70s which were far worse. The winter of 1962-63 was the worst, when it snowed on Boxing Day and didn't thaw until March - and this was in Slough, not the far north!
Winter of 1962
Also, I remember living in south Oxfordshire in the late 70s/early 80s when one winter nearly every plant in our garden was killed by the cold, and we were snowed in on several occasions.
MadameLaMinx is right - we just get to hear about it more these days.
People are always telling us that the end of the world is nigh - it has been "nigh" several times in my lifetime and we are still here!