A local precepting authority which has made calculations in accordance with section 50 above in relation to a financial year (originally or by way of substitute) may make calculations in substitution in relation to the year in accordance with that section.

None of the substitute calculations shall have any effect if the amount calculated under section 50(4) above would exceed that so calculated in the previous calculations.

Subsection (2) above shall not apply if the previous calculation under subsection (4) of section 50 above has been quashed because of a failure to comply with that section in making the calculation.