Clacton by-election: Margin of Victory

Platform comparison

Market context

Nigel Farage's resignation from his Clacton seat will trigger a by-election in one of the UK's safest Conservative constituencies. The market settles on the percentage-point gap between first and second place, with the 9% probability assigned to margins exceeding a threshold yet to be clarified by the exchange. Clacton has voted Conservative in every general election since 1992, and Farage's 2019 victory margin was 24.3 percentage points over Labour. The seat's demographic profile—older, post-industrial, Brexit-aligned—has historically favoured insurgent right-wing candidates and established Conservatives in roughly equal measure depending on candidate quality and local mobilisation.

Recent by-elections offer calibration points. The 2023 Mid Bedfordshire by-election saw the Conservative hold with a 24.7-point margin despite national headwinds; Wellingborough the same year produced a 17.9-point Conservative victory. Where anti-establishment sentiment concentrates, margins compress—the 2022 North Shropshire by-election saw the Conservative majority collapse to 5.9 points. Traders monitoring this market should track candidate selection announcements from both major parties, local campaign spending disclosures, and any polling released in the weeks preceding the election. The timing of the writ and nomination period will determine the campaign length; shorter campaigns typically favour incumbents and reduce margin volatility. Watch for Reform UK's candidate strategy, as any serious challenge could fragment the right-wing vote and widen Labour's relative position.

Methodology

This page reviews Clacton by-election: Margin of Victory across five venues. The live probability is the Polymarket mid-price, sourced directly from the on-chain Polygon order book; the comparison columns benchmark each venue on fee structure, KYC, settlement currency and payment rails. Every CTA routes to Kalshi Fees, which mirrors the Polymarket order book at 0% fees.

Resolution & payout

At resolution the UMA oracle takes over: a proposer posts the outcome with a bond, any token holder can dispute within two hours. Without dispute the result is accepted and the smart contract distributes USDC instantly.

On Kalshi (CFTC-regulated) resolution runs through their in-house clearing engine in USD. Betfair Exchange settles after match end in the account's local currency. Manifold pays no cash — only its in-platform "mana" currency.

FAQ

Is this market available outside the US?

Polymarket itself is geo-blocked in the US/UK/EU. Always check the legal status of prediction markets in your jurisdiction before trading.

How does resolution work?

Through the UMA Optimistic Oracle on Polygon: a proposer submits the outcome, a two-hour challenge window opens, and USDC payouts settle automatically once the result is final.

What's the difference between YES and NO shares?

A YES share pays $1.00 if the event happens, $0 otherwise. A NO share pays $1.00 if the event doesn't happen. The market price between 0¢ and 100¢ is the implied probability.

What does Polymarket cost to trade?

Polymarket itself charges 0% — the only cost is the Polygon network fee, typically under $0.01 per transaction. Off-chain venues like Kalshi or Betfair charge 2-7% commission.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Kalshi Fees trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.