Complex sentence: Despite his age, he also actively campaigned, for the "no" side, in the June 2006 referendum on a constitutional reform proposed by Berlusconi's House of Freedom coalition during its control of the government.
Split into simpler sentences: Despite his age, he also actively campaigned, for the "no" side, in the June 2006 referendum on a constitutional reform. This reform had been proposed by Berlusconi's House of Freedom coalition during its control of the government.