Her voice acting roles included Noddy in `` Noddy 's Toyland Adventures '' , Princess Sylvia in `` Muzzy in Gondoland '' , Trillian in the BBC radio series `` The Hitchhiker 's Guide to the Galaxy '' and Princess Eilonwy in the animated film `` The Black Cauldron '' .
Her voice acting roles included Noddy in the Cosgrove Hall/BBC Television series `` Noddy 's Toyland Adventures '' , Princess Sylvia in `` Muzzy in Gondoland '' , Trillian in the radio series `` The Hitchhiker 's Guide to the Galaxy '' and Princess Eilonwy in the animated movie `` The Black Cauldron '' .