By Jon Robinson Castore, the British sportswear brand backed by the likes of Sir Andy Murray and the billionaire Issa brothers, has slumped to a loss despite its sales jumping by £75m. The Manchester-headquartered business has reported a pre-tax loss of £28.8m for the year to 4 February, 2024, according to newly-filed accounts with Companies House. The loss comes after the brand posted a pre-tax profit of £14.6m for its prior 12 months. However, the new results also show its turnover surged from £115m to £190.3m over the same period. Castore’s accounts show that it incurred exceptional costs o…