Someone some day had to write a story about a boarding school without romanticism or self-pity, and this could have been it. The children [of Witch Week] fill familiar roles: Nan is unpopular, Estelle is pliant, Theresa is a bully, Charles a loner, Brian a victim, Simon a born leader. But they are living in a world in which witchcraft is dreadfully alive, where Guy Fawkes succeeded in blowing up the Houses of Parliament, and history developed differently. By a tremendous effort of witchcraft the two worlds are wrenched together again, and everyone comes to themselves in an ordinary comprehensive. It doesn't actually end 'So it was all a dream', but there is something of the same let-down that Diana Wynne Jones should have found a way of conveying the stifling conformity of a closed community and the crooked subterfuges the children develop to preserve their identity, and then refused to take her creation quite seriously. But it's still a good story.

Dorothy Nimmo, in her review of "Witch Week," in The School Librarian, Vol. 30, No. 4, December, 1982, p. 359.