March figures

A month rivaling December 2010 in how far the temperature deviated from the mean.
http://weather.westerdale.info/climatedataout32013.html

The first week was not unusual but around the 10th some very cold air arrived from the east and is more or less still with us 1st week of April.
The second half of March is probably the coldest such period in at least 100 years (1892 may have beat it)

March and indeed April will often have a few snowy days often associated with a brief Northerly.
This period has been quite different with a long fetch easterly bringing exceptional cold air for the time of year across most of Europe.
Germany for example has also been extremely cold.

Paul Hudson now says it has been the coldest March since 1892
http://www.bbc.co.uk/blogs/paulhudson/posts/Latest-weather-climate-news