Complex sentence: Luder served as a Sheriff of the City of London for 2007--08 and was elected Lord Mayor on 29 September 2008, taking office in the "Silent Ceremony" on 7 November.
Split into simpler sentences: Luder served as a Sheriff of the City of London for 2007--2008. He was elected Lord Mayor on 29 September 2008, taking office in the "Silent Ceremony" on 7 November.