John Lewis managing director Andy Street has ruled out opening stores abroad in order to invest in navigating a changing UK market.

The retailer, which yesterday opened its seventh shop-in-shop in a branch of South Korean department store group Shinsegae, will not be following rivals Debenhams and House of Fraser overseas.

Street told Retail Week: “We’re not going to run [standalone] John Lewis shops abroad. The UK market’s going through a tremendous change at the moment, I will not have us distracted, either in the management team’s efforts or the capital that we have.

“Capital for fulfilment, capital for IT, capital for omni-presence. They all have far greater return.”

Street, who picked up the Omnichannel Retailer of the Year Award for John Lewis at last night’s World Retail Awards, said retailers were faced with “hard choices” about where to invest capital.

He said that click-and-collect, mobile shopping, personalisation and delivery were areas of focus for the retailer as it vies to enhance its omnichannel business and his job was to allocate capital effectively.

He said: “We’ve already had to fundamentally shift our investment. It’s about hard choices. It’s not extra cash. We had to stop doing things in order to do this [investment in omnichannel].”

However, he said that “mindset” and engaging its staff were crucial to building an omnichannel retailer. “I don’t care where the sale is made. I don’t want my teams to worry, it’s a John Lewis sale. Everything has to be channel-agnostic. If you have that mindset everything else will follow.”

Sharing customer data with partners has helped them buy into his vision of an omnichannel business. “If you show them the facts, partners will do the right thing,” he said.

Street echoed Next boss Lord Wolfson’s concern about the warm weather in September impacting sales and said it spanned across more sectors than fashion. “It will be affecting everyone on the high street. People are just not going to shops,”

He said the key was to be patient. “If the weather changes in the first half of October it will basically be OK. If it doesn’t, there will be consequences,” he warned.

Despite the slow September, Street said he was “pretty optimistic” about Christmas because the economy was in the best shape it had been for seven years.

Online sales accounted for 35% of John Lewis’s sales last Christmas and Street expects it to surpass that level this year. He predicted that Black Friday would be an even bigger phenomenon and said the challenge this Christmas would be about “managing the surge in online demand”.

He also said this year would be a “mobile Christmas on steroids”. The retailer is launching a tranche of new apps ahead of the festive period to benefit from this trend.