The thing that I enjoy most about Welford's work is the feeling of adventure. Sure, you may be a little scared to make a time travel machine out of a bathtub and an old laptop, or if you turn invisible, but what an opportunity these situations present for children to venture out of their comfort zones in order to make positive changes in the world. The upbeat attitude in the face of adversity is always refreshing in middle grade stories, especially in speculative fiction, which has a tendency to turn a bit grim. Adding a farting dog goes a long way to brighten things up.
This was published in England before the COVID-19 pandemic, but has an extra layer of believability now that we have all seen how diseases can spread and have devastating consequences. This is an interesting mix of time travel and dystopia, and there's a growing list of plague dystopian novels to which this can be added, along with Lu's Legend, Chadda's City of the Plague God, Hirsch's Eleventh Plague, Ford's Z, and Burt's chillingly relevant Cleo Porter and the Body Electric.