The discount retailer B&M has said exceptionally strong demand for DIY and gardening products in the coronavirus lockdown drove a 22.7% jump in underlying UK sales over the last eight weeks. The group, which has traded throughout, said UK like-for-like sales growth had accelerated from 6.6% in the final quarter of its 2019-20 year, which benefited from a strong grocery performance in March. It said customers had been visiting its stores less frequently during the lockdown but their average spend had been much higher than usual. However, the business was experiencing larger-than-normal operating costs in distribution and its stores because of physical-distancing measures and higher wage costs during the crisis. It also warned there had been a significant “bring-forward” of demand in some key categories, partly caused by the warm spring weather. The chief executive, Simon Arora, said: “We are not expecting this current level of trading to continue as normal shopping patterns resume. There is also considerable uncertainty in relation to the progression of Covid-19 and the economic outlook, and it is therefore hard to predict future trading levels.” B&M shares were up 4% at £3.85 in morning trading on Friday, valuing the business at £3.85bn.