**Sagal Abdi-Wali leads the Holborn and St Pancras by-election market at 69% amid Keir Starmer’s early September 2026 resignation, which triggered the contest in the long-held Labour seat.** Labour’s selection process, closing applications on 4 September with a decision expected on 9 September, positions the Camden council leader—a local figure and former constituency party chair—as the probable nominee and strong favourite to retain the constituency. Green Party leader Zack Polanski’s confirmed candidacy has lifted his party’s implied chances into the mid-20s to low-30s range in betting markets, reflecting local Green gains in the May 2026 Camden elections and efforts to capitalise on progressive voter sentiment, though the seat’s history and Labour organisation keep the party’s overall win probability well below 30%. Other named candidates remain at single-digit or lower implied probabilities, consistent with the limited prospects for smaller parties or independents in this north London constituency. The by-election date remains pending the writ but is expected within the standard 21–27 working days once moved.