Set in rooms decorated as Hogwarts classrooms and evolving around the subjects tested in OWLS and NEWTS, this turned out to be a clever blend of Harry Potter paraphernalia and the sort of real-life historical documents you expect to find at a library exhibition.
I suppose most visitors learnt things they didn't know beforehand on historical takes on herbology, astronomy, potions, magical creatures etc, and at any rate the Harry Potter artworks by Jim Kay are a delight.
Rowlings has lent pages of handwritten and typed scripts and her personal sketches, initially intended only as memory-joggers. What stuck with me was the extent to which these pre-publication drawings were similar to the figures as we know them from the films. Directors and scriptwriters must have followed Rowlings's lead very closely.
Despite the suggestive presentation, however, this remains a literary exhibition and as such focuses on ancient books, thereby making more suitable for adult potterheads than young children.
Book in advance. It seems to be very popular.
And should the two museum gift shops prove insufficient for your merch-cravings, the 9 3/4-shop at the King's Cross is just a stone's throw away...