Avis uk and Avis ie quotation differences

I am renting a car in the uk this summer.

I was messing about looking for the best quote, trying Avis, Avis preferred, BA. Then I tried Avis Europe which turned out to be Avis Ireland.

The Avis Ireland quote is exactly the same as the Avis Uk quote but is in Euro while the Uk quote is in GBP. This works out to quite a big difference of about 70 GBP.

Is there any reason for the difference in the quotes?