With the Hamish cover, we knew right from the beginning that we wanted it to stand out on the shelves, to be as striking and eye-catching as we could make it. Hamish and the Worldstoppers, whilst being an hilarious story filled with fun and silliness, is also a story jam-packed with action and chaotic set-pieces, and I really wanted to get this across with the illustration. The monstrous Terribles, the villains of the story, really enabled me to do this: their very reason for existence seems to be to cause chaos, harm and disorder, and I thought it would be really fun to have them 'invading' the cover like they do Hamish's town of Starkley in the book, biting and scratching away at the text and sides of the cover, reaching towards our heroes, and basically causing as much damage and mischief as they possibly can. Simon & Schuster also suggested that we could use a really cool printing technique and have the Terribles bleeding out off of the spine and page-edges (outer spine? The ribs?) of the book, and this really added to that 'swarm' feeling I was trying to give to the Terribles (and one that I think looks especially cool and unusual on the final cover!).
As for the colours used on the cover, this was actually quite a simple step. Trying to make the cover as bold and striking as possible, we knew it was a matter of choosing a strong colour, we weren’t going to have any subtle colour gradients or textures, we were just going for bold and brazen, to really highlight the characters and text on the image, and to make it as eye-catching as possible. The Terribles themselves were kept mostly as silhouettes, not only because the solid, black shapes looked very graphical and imposing, but also so that they didn't distract too much from our heroes in the centre (and we didn't want to give away too much about what they were, we just wanted to suggest the beastly threat facing Hamish and co).
The final iteration of the cover changed quite a bit. The designer for Hamish and the Worldstoppers, Paul Coomey, and I, were worried that the cover was in danger of feeling a bit too cluttered. We wanted the Terribles to really seem like they were swarming the cover, but we didn't want the design to feel too suffocated. As such, we removed a lot of elements, such as the large clock-face in the background (which we'd rather liked, the story is about all of time stopping, after all!), and the sign some Terribles has been gleefully chewing which was meant to be there to hold the quotes that were to appear on the final design. Sadly, this also meant we had to remove Buster and some of the more realised Terribles, but now we felt as though there was a lot more room to breathe, and that the viewer could now really focus on Hamish and Alice, the two main characters of the story, making the cover all the more striking.