The Marmite supermarket row shows the Tories are “colliding with economic reality” after claiming there are no downsides to Brexit, a Labour MP said today.

Stephen Kinnock spoke out as Tesco’s row with supplier Unilever provoked headlines around the world as one of the most visible signs on the high street of the plunge in the value of the pound.

Kinnock, who is part of the Open Britain campaign, added to the Labour attack on the Government after ministers yesterday failed to answer the 170 questions tabled by Labour on the detail of Britain’s withdrawal from the EU.

“When the plunging pound stops you from getting PG Tips and Marmite in the supermarket, you’re truly starting to feel the first tremors of Brexit,” said Kinnock, a former executive at the World Economic Forum.

“David Davis’s claims that there were no downsides to Brexit are colliding with economic reality. The best thing the Government can do for economic confidence and the pound is to commit now to starting the upcoming negotiations on the basis of securing full and unrestricted access to the Single Market.”

Several big brands including Marmite, PG Tips tea and Ben & Jerry’s ice-cream were pulled from Tesco’s website, above, yesterday as the corporate dispute burst into the open. Unilever reportedly asked the grocer for a 10 per cent price increase after the pound fell to its lowest level since 1985. Sterling has fallen by 16 per cent against the euro since Britain voted to leave the EU.

Clive Lewis, the newly-appointed shadow Business Secretary, said several more other foodstuffs could be hit by the political uncertainty over Brexit.

“Once again the public are paying the price for Tory failure to make any contingency plans for Brexit. This is unlikely to stop at a Marmite shortage – more and more retailers are going to be squeezed by higher import prices in the coming months, as hedging contracts end and the cheaper pound starts to squeeze margins,” he said.

Read Labour’s 170 questions on the detail of Brexit