UK utility Scottish & Southern Energy said Thursday it now has around 8.5  million customers, making it the UK’s second largest supplier of electricity and gas. In an interim report on its performance, mainly covering the April to December 2007 period, SSE said that it had gained 650,000 customers in the last nine months of 2007, taking its total base to 8.4 million at the end of 2007. It then gained further in January 2008. The biggest supplier is Centrica, which markets as British Gas. It has just under half of British homes signed up for gas and about a quarter for power. SSE said its customer complaint numbers were down too. The number of complaints to Energywatch was 495, down 22% from the same nine months of 2006.  Financial results for 2007-08 as a whole are expected to be in line with the current consensus of brokers’ forecasts.