Nicola Byrne founder of 11890 directory service is urging consumers to buy online to avoid currency differentials

Abig retail mystery remains. Even as euro gets stronger and stronger against sterling, the huge advantages of the mighty euro are still not being passed onto local shoppers in the south to render redundant 250km round shopping trips to buy Pampers, booze and clothes all made in factories in Britain or sourced from massive wholesale and distribution centres across the Irish Sea in the first place.

Significantly, the Competition Authority and the National Consumer Council – the two bodies supposedly charged with looking after the consumer interest – are almost invisible on a matter of basic economics of the mighty euro's strength.

The euro, or the old basket of currencies like the former deutschmark and the old French franc, has not been higher against sterling any time since 1996.

The Republic, like no where else in Europe, should be benefiting from massive price falls, not relatively small differences because so many of the foodstuffs and most hard goods are imported from across the Irish Sea.

It's called a strong currency for a reason: it's supposed to bring buying strength or might when we buy things from other currency zones, such as Britain. We have heard most about the disadvantages of a strong currency – it undoubtedly makes life very difficult for exporters into Britain. But the huge benefits are being overlooked, helping to mask continuing rip-offs.

Three years ago, in November 2006, the euro was worth only 67 pence. The euro soon started to bulk up. A year later it rose 5.5% to 71p. Last year, €1 bought over 82p, a rise of 15.5% in one year. The mighty euro continued to grow stronger.

This week €1 bought 90p of sterling goods, meaning that since late autumn of 2006 the euro is now worth 25% more than sterling.

That surge for the currency against sterling is, significantly, roughly reflected in the prices charged in northern stores. Yet, only a fraction of the difference is being passed onto southern shoppers in their local shops.

In many cases, all of the purchasing might of the euro is being pocketed by manufacturers and/or retailers.

How do we know this is the case? Well, the facts are hidden in detailed figures the Central Statistics Office (CSO) publishes every month. The Sunday Tribune asked the CSO to analyse prices paid across a huge range of goods and services this autumn in shops, and to compare them with the prices charged in autumn 2006, before the euro started to rise against sterling.

We asked the CSO to specifically focus on 55 categories of foodstuffs, many of which are sourced in Britain. If the currency benefit was being passed onto local shoppers then the huge 25% growth in the muscle power of the currency should be reflected in huge price falls in goods that are sourced in Britain. Instead, the prices cuts are meagre and in some cases do not exist.

The 2.4% rise since autumn 2006 in all foods masks huge price increases in specific food stuffs. Bread and cereals together, despite the euro's 25% appreciation, have risen 8.3%.

Bread products have surged 19.1%, and flour has soared 35%. The price of biscuits has fallen about 2.5% in the last three years but cakes have climbed 6%. Breakfast cereals have fallen marginally this autumn from 2006 prices by a small 2.6%, but other cereals have soared almost 12.5%. Meat prices are little changed from late 2006, while beef prices charged in stores have risen 4.7% and lamb has risen by over 3%, while pork, bacon and poultry have fallen 5%, 6.5% and 5.8%, respectively.

Fresh fish prices have fallen 2.7%, but frozen, tinned and smoked fish products have climbed 3.7%. Together, the price of milk, cheese and eggs charged by stores have climbed 17.5% in the last three years – milk prices have surged 27.5% and eggs are 15% more expensive. Oils and fats are 11.3% more expensive, butter is 13% dearer and margarines are 13.7% more expensive.

A 6.8% fall in fresh fruit in the last three years still does not reflect the 25% gain in the euro over the same period. Vegetable prices have fallen 6.5%. Potatoes – many are sourced from the sterling zone in Co Down – are appropriately down by 19% and other fresh vegetables have fallen by 4.2%. But tinned vegetables have risen by a remarkable 14.6%, even as frozen vegetables have fallen by 7.5%.

The anomalies continue. The prices of preserves have soared almost 8%, sweets and chocolates have risen 3% and soup prices have risen 5.3% in the last three years. Tea prices have risen 4% and cocoa have surged 8.5%, despite the 25% surge in the euro over the same period, even as the price of coffee has fallen about 5.5%.

In services, there are even bigger price hikes in the last three years which have little to do with euro surge – health insurance is up by 30.5% in three years, house insurance by over 26% and third-level education prices have risen 34%, says the CSO.

There is, however, a stunning example of the benefit of the 25% surge in the euro failing to be passed on to consumers – the CSO figures show that the price of package holidays since autumn 2006 have surged 9%. Despite the buying power of the euro, package holidays have risen 5.5% in the last year alone.

The Sunday Tribune looked at the price of package holidays in Britain, where, in the past year prices rose by 6.2%, according to its National Statistics Office. They have risen by about the same amount here even though sterling has slumped 9.5% against the euro in the same period.

Beat the rip-off Republic online

Nicola Byrne , founder of 11890 directory enquiry service, says she is about a week away from launching a new personal shopping service to "beat the rip-offs of big manufacturers pricing goods at outrageous prices" in the Republic. "The genesis of the site, Haveitposted.com, is that there is no justification in the prices being charged here," she says. "The first three things that I saw were Ugg boots selling here for €279 ($419) which were $140 in the States. Then there were Abercrombie and Art of Shaving oil goods. Even paying the 21.5% Vat and the shipping you can get it cheaper. Then you wonder who is getting the money. But people were prepared to pay it. We never moaned," says Byrne. Laptops, printers and red-soled Christian Louboutin shoes – almost everything, she says – can be sourced online by personal shoppers and legally posted back to the Republic. Other people are pocketing the purchasing strength of the euro, she says. She says the directory-enquiry business she runs in the north has opened her eyes to retail prices north and south. In Derry, costs such as a full Irish breakfast to car parking are significantly lower. "Sure, the minimum wage is lower in the north. But it is not to do with wages and costs," Byrne says.