Britain's biggest sportswear retailer JJB Sports scored a big jump in first-half pre-tax profits on Wednesday and said it had kicked off a strong start to the second half, sending its shares higher. The company reported an increase in same-store sales during the first half to the end of July up 9 per cent, while same-store sales for the first nine weeks of the second half were up 8 per cent. The company said that current trading following the September 11 attacks was "entirely satisfactory".