21. Tirupporur

Dravida Munnetra Kazhagam held the seat; the winning margin narrowed from 21.6% to 3.8%.

Boundaries were redrawn between 1971 and 1977 — the comparison is matched by name and is indicative only.

• Won on a lower shareIts own vote share fell 12.2% — it held because the rest of the vote was more divided.
• New challengerAll India Anna Dravida Munnetra Kazhagam (AIADMK) finished second with 41.0% — it did not contest here in 1971.
• Vote fragmentedThe top two took only 85.8% between them, down from 92.4% — the field split more ways.

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