When I hear/read the name "Lucan", memories of this case are my first reaction. The Seventh Earl of Lucan has not been seen since the night of November 7th, 1974, when his children's nanny was beaten to death with a piece of lead pipe, and his estranged wife was attacked [She staggered for help to a pub called The Plumbers' Arms; would you write that?]. Some months later an inquest jury declared him guilty of murder. He was officially declared dead in October 1999 so the family could settle inheritance & so forth, but speculation, rumour & theorising continues.
This spot has a pretty good summary of the history for the 20th anniversary last year, and links, such as Lord Lucan.com, The Lucan Review, and Last Person [known] To See Lord Lucan Alive Dies (in September 2004).
You can find a whole lot more -- about 22,400 results in the UK for "Lord Lucan" on google.co.uk, for instance. I think I'm not unhappy that I've never heard of the other Lucan mentioned above. (Lucasian OTOH, leads to a whole other universe ...)

Moodiness: relaxed