Thanks for your comment Dick - as a respected member of uk.sci.weather, I have spent some time looking back just in case there has been s statistical error, which is always possible considering the vagaries of data enties into Excel.

However I have checked our records, and spring 1967 did it seems have an average of 6.9C in Coventry compared to 7.0C in 2013.

I even went back to 1967 files for individual months and found

1967 March ave 4.5C 2013 2.5C
1967 April ave 7.0C 2013 7.7C
1967 May ave 9.1C 2013 10.9C

Of the other springs that you mention

1968 = 7.6C
1975 = 7.6C
1979 = 7.8C
1984 = 7.7C

The coldest Springs in our records are

1962 = 6.6C
1941 = 6.7C
1951 & 1967 = 6.9C
2013 = 7.0C
1969 = 7.1C

Not sure that I can explain any unexpected variations with the CET records comparison.

best wishes

Steve J