Hi Alex,
I agree with Eowyn for de.
It should be the same for le (and not Le): for example: Pierre le Grand, not Pierre Le Grand.
AFAIK, the British way of wording is often nearer (for some patterns) to French than the USA way.
PS If you want to see how complex this simple matter is, go here:
http://www.btb.termiumplus.gc.ca/red...psect3&info0=3 and look 3.3.9 Noms de famille: this is daunting, but useful!