If you are prepared to fly rather than get the ferry, the Irish Sea has some of the lowest fares in the world / AFP/Getty Images

'At the root of the price difference is, of course, supply and demand'

Q| My husband and I would love a holiday home in either Ireland or northern France. Why are ferry prices to Ireland so expensive? It’s much cheaper to travel to France. Is there a reason ferries to Ireland are prohibitive?

Andrea Scott

A| It’s difficult to assess because all ferry routes have different characteristics. I have looked at two links, one between England and France and the other between Wales and Ireland. The Newhaven-Dieppe and Fishguard-Rosslare routes are operated only by one firm, and both are about 70 miles apart. I looked at daytime sailings for a car and two people on 19 September, returning a week later.

The difference is remarkable: the Fishguard-Rosslare fare on Stena Line is £318, while for Newhaven-Dieppe on DFDS it is £164 – barely half as much. So what is going on? At the root is, of course, supply and demand - with demand heavily influenced by the availability of other options - which, on links to France, are many and highly competitive. Anyone who thinks the Newhaven-Dieppe fare is unappealingly high need only aim another hour east and take one of the many options between Folkestone/Dover and Calais/Dunkirk. For example, DFDS charges £98 for Dover-Calais and £90 for Dover-Dunkirk on the same dates. For the Irish journey, though, Stena Line’s Holyhead-Dublin fare is exactly the same £318 as the southern option.

Yet if you are prepared to fly, the Irish Sea has some of the lowest fares in the world. On the same dates, between Stansted and Cork you would pay £75 each return – and by adjusting the day of travel it is easy to find £40 fares. Cork airport is well located for Kinsale and other lovely coastal towns.