“Rein Me In” first reached number one on the UK Singles Chart in February 2026. It reached the summit on 26 February after a 35-week climb on the chart.
The result marked Sam Fender’s first UK number-one single and Olivia Dean’s second. The song had initially entered the chart at number 86 before rising to number six the following week, making its eventual climb unusually long for a chart-topper.
That extended journey is why the month matters: the duet was released in June 2025 but did not reach number one until the following February. The answer is therefore February, not January or March; those options confuse the release period or later chart activity with the first week at the summit.