On Friday, finance minister Kwasi Kwarteng outlined plans for deep tax cuts and deregulation to snap the economy out of a long period of stagnation, triggering financial chaos.

But Next CEO Simon Wolfson said the UK needed supply side reform, particularly in terms of planning, economic migration and energy supply.

"Whether or not this project is a success or not will depend on two things," he told Reuters.

"Are they able to introduce the supply side measures that genuinely liberate the economy to the extent that the growth pays for the stimulus package?

"And secondly can they balance the books by cutting out some government expenditure that is wasteful or not necessary?"

Wolfson said the government should, for example, review the HS2 high-speed rail link.

Wolfson, who also sits in the upper house of Britain's parliament as a Conservative peer, was speaking after Next reported first-half results.

(Reporting by James Davey, Editing by Paul Sandle)