What is a free port? All you need to know about the free-trade zones

Plans have been mooted for tax-free zones to offset post-Brexit tariffs. But are they needed? And do they actually work?

• Lux goods: inside Luxembourg's warehouse for the super-rich

Boris Johnson is considering establishing free ports in the UK if he succeeds Theresa May as UK prime minister in July. Belfast, Teesside and Aberdeen are among potential sites for the tax-free economic zones.

Related: Belfast could be Singapore-style tax-free zone, says Johnson