The boss of Wetherspoons (LON: JDW) called on Theresa May to leave the customs union and remove taxes on non-EU drink and food imports.

Brexiteer Tim Martin used the pub chain’s slowdown in sales growth to push for the UK’s departure from the EU customs union and instead adopt free trade policies seen in New Zealand and Singapore.

“I feel sure that the UK should leave. This will enable parliament to eliminate taxes on non-EU food and drink imports, reducing prices in the shops, which will immediately improve living standards,” said Martin.

“It makes no sense for the UK to continue to impose taxes on New World wines, coffee, rice and thousands of other products, and then to send the proceeds to Brussels. The EU masquerades as a free trade organisation, but it is really a protection racket which imposes import taxes on the 93 percent of the world’s population that is not in the EU.”

Boris Johnson has attacked Theresa May for her proposed customs union partnership, calling the proposal “crazy”.

Johnson told The Daily Mail that the system would make it very difficult to carry out free trade deals and would not deliver on the result of the referendum.

Sales in the group grew at a slower pace than expected in the third quarter, reporting a three percent increase in like-for-like sales in the 13 weeks to 29 April.

Wetherspoons attributed the lower sales due to this year’s timing of the bank holiday, which accounted for 0.5 percent of sales.

Martin also blamed the slowing growth on the group’s significant increase in costs of labour, business rates and sugar tax.

“There is also some uncertainty as to the effect on sales of the FIFA World Cup,” he added.

“We continue to anticipate a trading outcome for this financial year in line with our previous expectations.”