The list of voters for any electoral division which has been published and has come

into operation under sub-section (7) of section 20 shall, subject to any revision made under the proviso to this section, remain in operation until a new list of voters for that electoral division is prepared, published and comes into operation: Provided that the State Election Commission may, after consulting the State Government for reasons to be recorded in writing, direct that such list for any electoral division may be revised in the prescribed manner by reference to the qualifying date, before any bye-election is held to fill a casual vacancy in a seat allotted to that electoral division.