51. Kollengode

Communist Party of India (Marxist) held the seat; the winning margin narrowed from 24.9% to 0.7%.

Boundaries were redrawn between 1970 and 1977 — the comparison is matched by name and is indicative only.

• Won on a lower shareIts own vote share fell 9.1% — it held because the rest of the vote was more divided.
• New challengerCommunist Party of India (CPI) finished second with 45.4% — it did not contest here in 1970.
• Vote consolidatedThe top two candidates took 91.6% of the vote between them, up from 85.5% — a tighter two-way contest.

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