Right... apologies to Gilbert and Sullivan... here goes

ALL:    Three Lancre Witches, that's we three
        Out on a summer spelling spree
        Filled to the brim with pots of tea
        Three Lancre Witches we!

Magrat: Everything is a source of fun
Granny: Starting my stick takes a good long run
Nanny:  You won't believe all the things I've done
ALL:    Three Lancre Witches we.

        Three Lancre Witches, all be wary
        We don't believe in airy-fairy
        Hide from our powers fulminary
        Three Lancre Witches we,
        Three Lancre Witches we!

Magrat: One Lancre Witch is a Maid, you see
Nanny:  Mother and Crone the remainder be
Granny: Nobody say which witch is me!
ALL:    Three Lancre Witches we!

Magrat: One Lancre Witch got married one day
Nanny:  Two Lancre Witches remained, and they
Granny: Searched for a new one straight away
ALL:    Three Lancre Witches we!
        Three Lancre Witches we!

        Three Lancre Witches, all be wary
        We don't believe in airy-fairy
        Hide from our powers fulminary
        Three Lancre Witches we,
        Three Lancre Witches we!

Suzi
(with a little help from Gid)