5The electorate of any constituency shall be as near the electoral quota as is practicable having regard to rules 1 to 4 ; and a Boundary Commission may depart from the strict application of rule 4 if it appears to them that a departure is desirable to avoid an excessive disparity between the electorate of any constituency and the electoral quota, or between the electorate of any constituency and that of neighbouring constituencies in the part of the United Kingdom with which they are concerned.