Right to hearing secured: opportunity to be heard, further enquiries allowed, new objection grounds limited unless excused. The authority deciding an objection must afford the objector or an authorised representative a reasonable opportunity of being heard unless personal hearing is expressly waived; it may direct or cause further enquiries, including by the authority against whose decision the objection is preferred, and may refuse to admit any ground of objection not originally specified unless omission of that ground was not willful or unreasonable.