For the sake of 'Pabha Vimochanam', Indiran came to Earth and worshipped Linga by installaing various Lingams. A temple was later built on one of such Lingams at Ilayangudi. The God if named by the name of KIng who ruled that place & called it 'Rajendra Choleeswarar'. Another feature: Lord Muruga is with Deivanai only with out Valli. Reason being that since Indiran has installed & worshipped lingam, his daughter Deivanai only is present.
Look like another Grand old siva temple in Tamilnadu with out much attention.