Can't remove holidays

[John Martin]

I have the following in my .emacs file in order not to show US holidays

(setq holiday-general-holidays nil)
(setq general-holidays nil)

I should probably only need one of the above lines but I'm not sure which.
Neither line works, I still see US holidays.

The following lines come from the holidays.el.gz file and appears
to describe my problem however I don't know how to correct it,
how do I tell what's being autoloaded?

------------------------------------------------------------------------
;; This one should not be autoloaded, else .emacs changes of
;; holiday-general-holidays etc have no effect.
;; FIXME should have some :set-after.
(defcustom calendar-holidays
  (append holiday-general-holidays holiday-local-holidays
      holiday-other-holidays holiday-christian-holidays
        holiday-hebrew-holidays holiday-islamic-holidays
           holiday-bahai-holidays holiday-oriental-holidays
              holiday-solar-holidays)
------------------------------------------------------------------------

Presumably I shouldn't be touching the files in the emacs distro,
any ideas what I'm doing wrong?

-- 
John