Well, Purple Ronnie is sort-of a character, but yes, there is a single real person behind it, one Giles Andrae. Here's a bit of blurb about him: http://www.orchardbooks.co.uk/gandrob.htm
Thanks jenstar. That's an interesting site you led me to. TW - yes, I find the cards amusing and quite touching as well. I can often be seen chuckling away in the aisles of Clinton's and Birthdays!!