Labour's Jo Potter has won the Grays Riverside by-election in Thurrock, taking the seat back from Reform UK in a tight three-way contest that was far closer than the neighbouring Grays Town result declared the same night.
Potter secured 389 votes (30.2%), narrowly ahead of Reform UK's Jason Mitchell on 362 votes (28.1%) and the Green Party's Pauline Weir on 354 votes (27.5%). The Conservatives' Srikanth Panjala finished fourth with 182 votes (14.1%). Turnout was 6.3%, with 1,294 votes cast, only a fraction of the electorate taking part compared with the parallel by-election in Grays Town.
Part of a Double Labour Win in Grays
Grays Riverside was one of two by-elections held in Thurrock on 23 July, alongside Grays Town, where Labour's Amin Hoque won more comfortably against Reform UK. Both seats had been held by Reform UK since the party's sweeping gains across Thurrock at the all-out council elections in May 2026, and both wards had previously been considered safe Labour territory before that result.
Unlike the clearer margin in Grays Town, the result in Grays Riverside came down to just 27 votes separating first and second place, with the Green Party running both Labour and Reform close for the seat.
Why the Seat Was Vacant
The by-election was triggered by the resignation of the sitting Reform UK councillor. Neither Thurrock Council's official notice nor local reporting gave a detailed reason for the departure.
What It Means Locally
Combined with the Grays Town result, Labour's win in Grays Riverside hands the party two seats back from Reform UK in a single night, though Reform UK retains a substantial majority on Thurrock Council overall following its dominant showing in May. The closeness of the contest, and the strong showing from the Green Party, suggests the ward remains genuinely competitive between three parties rather than reverting straightforwardly to its pre-2026 Labour lean.