UPDATE 1-Pottermania returns with London world premiere

* Premiere ends two-year wait for Potter fans

* Half-Blood Prince is sixth of eight films

(updates after red carpet)

By Mike Collett-White

LONDON, July 7 (Reuters) - The new Harry Potter film had its world premiere in London on Tuesday, ending a two-year wait for faithful fans who have been counting down the days before its theatrical release on July 15.

Hundreds of people braved heavy rain in central London to watch the teenaged stars of "Harry Potter and the Half-Blood Prince", the sixth of eight films based on the novels by British author J.K. Rowling, walk down a sodden red carpet.

Fan Sharon held up a sign which read "Dan Marry Me", a reference to Daniel Radcliffe who has played Potter throughout the movie franchise.

"I've been here every year and he hasn't given me a reply yet, so hopefully today," she said.