Complex sentence: With the Ulster Orchestra, Montgomery served as its Principal Guest Conductor, and in September 2006, the orchestra announced him as their Principal Conductor effective in September 2007, the first Belfast-born musician named as the orchestra's Principal Conductor.
Split into simpler sentences: With the Ulster Orchestra, Montgomery served as its Principal Guest Conductor, and in September 2006, the orchestra announced him as their Principal Conductor effective in September 2007. Montgomery is the first Belfast-born musician named as the orchestra's Principal Conductor.