(S (S (S (BASENP (NNP Henley)) (VP (VBD called) (PP (IN for) (BASENP (DT an) (NN election))))) (SBAR (WHADVP (WRB when)) (S (BASENP (PRPD its) (NN representative) (NNP Boris) (NNP Johnson)) (VP (VBD was) (VP (VBN elected) (NP (BASENP (NNP Lord) (NNP Mayor)) (PP (IN of) (NP (BASENP (DT the) (NNP City)) (PP (IN of) (BASENP (NNP London))))))))))) (PERIOD .))