Asos’ soaring UK sales are down to self-help rather than any improvement in the economy, according to boss Nick Robertson.

He told Retail Week that the action it had taken since its domestic sales growth slowed two years ago in the face of younger shoppers becoming increasingly cash-strapped had helped propel the business, which jumped 49% in the UK in its fourth quarter to August 31.

“They’re great numbers, especially in the UK, compared with where we were a couple of years ago [where sales growth slowed]. But don’t read anything into macro-economic conditions this is a self produced turnaround. It’s the price activity, the improved delivery, the later cut-off for delivery,” he said.

Robertson said he was “chuffed” that Asos’ more established markets of the UK, France and Germany were driving growth. He said that having people on the ground was helping to grow sales.

Robertson predicted that it would be a “strong Christmas” for online retail. However, he warned that the big issue would be capacity of carriers delivering orders. He said Asos delivery would not be affected. “Suffice to say the bigger players will get preferential treatment,” he said.

Robertson declined to comment about Primark’s imminent departure from its website after its pilot launch in June, other to reiterate that it was designed as “a trial”.

Asos has raised full-year profit expectations after strong trading in the fourth quarter. It reported a 47% rise in retail sales to £208m in the three months to August 31, while sales in the year to the same date rose 40% to £754m.