It sounds a familiar story - a royal playboy heir with a lifestyle funded by other people getting involved in a sex scandal. However, in this particular case, the Royal is Prince Albert II of Monaco. And unlike the British heir to the throne (and perhaps strangely for a man named after a type of penis piercing), his scandal involves heterosexual sex, rather than a sordid homosexual romp with his manservant.
Prince Albert had admitted fathering a child with a French air stewardess and there are rumours of plenty more. Coincidentally Prince Albert's father changed the constitution according to the BBC:
Prince Albert, often dubbed the "playboy prince", has for years appeared reluctant to get married or start a family, which perhaps prompted his father to change Monaco's constitution in 2002.
Previously, the principality would have become part of France in the absence of a male heir. Rainier had the law changed so that, in the event of Albert remaining childless, Princesses Caroline and Stephanie could follow their brother, who was proclaimed regent during Rainier's last days.
Under Monaco's constitution, a child born out of wedlock doesn't count as an heir.
BBC News - Monaco prince admits love child