SALLY GAP - and a conundrum!

Last month, I visited one of the most beautiful countries in the world. Yes, I'm talking about Ireland!I went to the County of Armagh ("sure, there's one fair county in Ireland, with memories so glorious and grand....") and I also went to Dublin to stay with the talented and occasionally hilarious Abby Green, whose books you will know and love. Abby has worked (and sometimes still does) in the film industry and she took me to Sally Gap, just outside Dublin. It gives stunning views over the Wicklow mountains, which is why it is so beloved of film-makers.Here I am, on a day so windy that I honestly thought I might fly away.
But I am left with one question.Who was *Sally*?