Don't know mate but I think it was probably one from a reputable pollster.
Much as you and others don't like it there is a majority in support of the Monarchy. It doesn't mean there all sycophants, wetting themselves over the Royal birth dressed up in Union jacks waiting outside the Palace. Some people are just happy with what we have and cherish it. Personally the TV coverage has been (as normal) over the top, she's had a baby, it's a boy, let's move on. But if you don't like it, switch over.
And the old we are all born equal argument from the anti-monarchy guy on the Beeb last night, well no, none of us are born equal FFS, never have been and never will be.