That's partly because it's in the same timezone as Poland. Madrid is further west that London, but London is an hour behind. Moving Spain to permanent DST puts it on the same effective timezone as London.

http://blog.poormansmath.net/images/SolarTimeVsStandardTime....

Without the DST offset, Spain much more "red" than England.

It's not so much a "permeant DST" but rather a "we want to change to GMT without moving out of the CET timezone."