Is central European time always one hour ahead?
Yes, all time changes in the EU are co-ordinated so they all happen at the same time, and have officially done so since 2002. The present rule of summer time running from last Sunday in March to last Sunday in October has been in effect since 1981 in the UK, before that summer time started 1-2 weeks earlier. The dates of the start and end of summer time used to be decided by Parliament a few years at a time e.g. 1950-1960, it usually ran from mid-April to early-October.