Falls in shop prices for clothing and footwear deepened in the UK in May, leading to deflation in overall shop prices for the first time in more than three-and-a-half years.

Shop prices fell by 0.1%, according to the BRC-Nielsen Shop Price Index, with non-food deflation accelerating to 1.5% from 1% in April, its lowest figure since June 2009.

Clothing and footwear deflation reached 5.7% in May, down from 4.7% in April, with women’s wear, men’s wear, children’s wear and footwear all reporting acceleration in their deflation rates.

All sub-categories are now in deflationary territory, the Index reported, with babywear slipping into annual deflation during May.

Discounting increased during the month, with clothing and footwear both affected by unsettled weather, despite a sunny start to the month.

“This led to a greater use of discounts and promotions, particularly on spring products, to stimulate demand, while marked down knitwear was displayed longer than normal,” the report noted.

BRC director general Helen Dickinson said the report bore out the retail sales figures released a day earlier, which had suggested that retailers had used promotional tactics to drive sales of seasonal stock.

“Non-food deflation accelerated to its lowest level in almost four years, a reflection of the intense competition to capitalise on improving consumer confidence and the late onset of warmer weather,” she added.