just because 2007 was a good april turning into a poor summer doesnt mean that is the usual trend. . . 2003, 1999,1997,1995,1990,1984,1955,1949,1933 all had dry/warm aprils that lead to some decent to outstanding summers
The NW-SE split was most noticeable on the 10th july 2010. the heatwave in the south east spread as far as North Yorkshire and it was 26C in the Yorkshire dales and eastward. whereas 20 miles west in Cumbria the maximum temperature was 18C and cloudy, possibly even raining if i remember.
What is even more amazing is there is only 4 months with a lower mean minimum CET, being Feb 1895, -5.1 Jan 1963, - 4.8 Jan 1940, -4.5 Jan 1881 -4.3 December 2010, -3.8 Feb 1947, -3.8