To advertise a "SALE" price in the high street, the goods must have been offered at a higher price for a continuous period of twenty eight days within the last six months.
The term "DUTY FREE" is highly misleading as it implies that the item is being sold for a price significantly lower than normal as no duty is being charged.
To qualify to be advertised "DUTY FREE" the goods should be offered at normal retail price less the amount of duty which would be charged if they were sold land side.
I have no objection to shops selling alcohol and cigarettes at the airport but unless the whole saving is being passed on to the customer the "DUTY FREE" signs should come down. Instead let them give comparison prices with the high street instead to show what savings if any are being made.