5. Oupalam

All India Anna Dravida Munnetra Kazhagam held the seat; the winning margin narrowed from 15.9% to 3.6%.

Boundaries were redrawn between 1974 and 1977 — the comparison is matched by name and is indicative only.

• Won on a lower shareIts own vote share fell 10.1% — it held because the rest of the vote was more divided.
• New challengerJanata Party (JNP) finished second with 33.1% — it did not contest here in 1974.
• Vote fragmentedThe top two took only 69.8% between them, down from 77.8% — the field split more ways.

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