84. Mettur

All India Anna Dravida Munnetra Kazhagam held the seat; the winning margin narrowed from 22.5% to 18.6%.

• Won on a lower shareIts own vote share fell 10.1% — it held because the rest of the vote was more divided.
• New challengerIndependent (IND) finished second with 29.5% — it polled just 0.3% in 1980.
• Vote fragmentedThe top two took only 77.7% between them, down from 94.0% — the field split more ways.

Written from the constituency figures by a fixed set of rules — no language model.