Vacancies after full-Council elections

Question

When full-Council elections where the membership is duly elected uncontested after there were less candidates than vacant seats, can a by-election be demanded to fill the vacancies or does the new cohort of Councillors have to be given opportunity to co-opt first?

Answer 1

After an election for all council members, if the parish council is quorate, i.e. at least three and at least one third of the total seats on the council are filled, the elected councillors may co-opt councillors to fill the remaining seats.  For more info on other situations that could arise please see here https://www.electoralcommission.org.uk/guidance-returning-officers-administering-local-government-elections-england/casual-vacancies-and-elections/unfilled-seats-a-council-election

Answer 2

There is a period - I think 6 months without checking - after an election where authority to co-opt is automatic.
If there were insufficient candidates at the main election it is assumed there would similarly be insufficient for a by election so what’s the point of incurring the expense.