name the office holder with successor as richard onslow and child as martin attlee ?
SELECT DISTINCT var_uri where brack_open var_uri dbo_child dbr_Martin_Attlee,_2nd_Earl_Attlee sep_dot var_uri dbp_successor dbr_Richard_Onslow,_5th_Earl_of_Onslow sep_dot var_uri a dbo_OfficeHolder brack_close