Mirror Dreams, was completed when she was just 14 years old. The book was published in 2002 and garnered comparisons with Terry Pratchett and Philip Pullman.
Webb went on to publish a further seven young adult novels under her own name, earning her extensive critical acclaim and two Carnegie nominations for her novels Timekeepers and The Extraordinary and Unusual Adventures of Horatio Lyle.
Under the open pseudonym Kate Griffin, Webb has also since published a further six fantasy novels for adults. Dubbed the Matthew Swift and Magicals Anonymous novels, these books are set in an alternate modern-day London saturated with magic. They revolve around the concept that the pulse, the rhythm and the heartbeat of the city and the millions of people living within it becomes a palpable form of magic itself.
In 2014, Catherine released The First Fifteen Lives of Harry August under the pseudonym Claire North. It is the extraordinary journey of one unforgettable character who lives his life over and over again. It became a paperback bestseller and was selected for the Richard and Judy Book Club, the Waterstones Book Club and the Radio 2 Book Club.
A lifelong Londoner, Webb describes herself as a fan of big cities, urban magic, Thai food and graffiti-spotting, and she is endlessly fascinated by such questions as who leaves copies of the yellow pages on top of bus shelters, how the hidden tunnels beneath the sorting office were built, and why anyone would ever dispose of perfectly good pairs of shoes by throwing them over the nearest telephone line.