d. Insufficient candidates at an ordinary election

Where an insufficient number of candidates are validly nominated at an ordinary local council election to fill the council seats, those who have been validly nominated are automatically elected as councillors (s. 21, Representation of the People Act 1985). 

If those elected constitute at least a quorum (three or one third of the total number of seats, whichever is the greater), the council may co-opt eligible persons to fill the vacancies. It is good practice for councils to advertise such vacancies to attract possible candidates but, unlike casual vacancies occurring at other time, there is no legal requirement to do so.

If the power of co-option is not exercised within 35 days (in calculating which, Saturday, Sunday, Christmas Eve, Christmas Day, Good Friday, a Bank Holiday and a day appointed for public thanksgiving or mourning are excluded), the principal authority has wide reserve powers to do anything necessary to constitute a council properly (s. 39(4)(b) of the 1983 Act). 

If there are insufficient elected to constitute a quorum, the district council will call a second election within 35 days. Guidance issued by the Association of Election Administrators recommends two further elections are attempted before the principal authority considers exercising its powers under s.91, Local Government Act 1972, which enables them to APPOINT councillors, to the parish council. In practice, such appointees often include district councillors or former parish councillors.