Well in looking for some idea of just how many redheads there are in Ireland, I came across the following from Wiki posted on another discussion board:

"Scotland has the highest proportion of redheads, as 13 percent of the population has red hair and approximately 40 percent carries the recessive redhead gene.[8] Ireland has the second highest percentage; as many as 10 percent of the Irish population have red, auburn, or strawberry blond hair.[9] It is thought that up to 46 percent of the Irish population carries the recessive redhead gene. Red hair reaches frequencies of up to 10 percent in Wales.[10]"

My great-grandmother had red hair and was Scottish. I recently found out my mom's maternal ancestors were also Scottish, not English as we'd thought all of these years, so it looks like both of my parents had the recessive gene. From what I've read they both have to have it to produce a redhead.

There's also an interesting article about redheads becoming "extinct" as the numbers seem to be dwindling HERE. It includes some quotes from National Geographic.