Though ignored by everyone until it was time for his scars to be exhibited before them, he heard of major advances in medicine, engineering, mathematics and natural philosophy. A habitual thief, he continued to steal. With no pockets for his booty, he stole ideas and facts, committing to memory each detail of every lecture. (p.3)
One night in Victorian London a common thief, fleeing police, falls through a skylight: gravely injured, he becomes the pet project of master surgeon Dr Farcett, who saves his life. Charged under the name 'Montmorency' (from the brand name on his stolen bag of tools) he spends the next few years in prison -- the sheer monotony of it relieved by the occasions when he's taken to meetings to illustrate Dr Farcett's pioneering techniques. During one of these excursions he hears a lecture by Sir Joseph Bazalgette, father of London's sewer systems, and has an Idea.
Once released from prison, Montmorency -- who is a sharp one -- is determined to leave his former life behind. Not the crime, of course: just the grinding poverty. He embarks on an ingenious scheme involving two personae: Scarper, a greasy-looking fellow who can pass as a commoner or a servant, and Scarper's employer Montmorency, apparently a titled gentleman, who quickly becomes known as a man of (stolen) wealth and (borrowed) taste.
Despite this being a book for children, Updale doesn't flinch from the less salubrious aspects of Victorian life. Scarper takes lodgings with a mother-and-daughter team of prostitutes; Montmorency witnesses and experiences man's inhumanity to man (and animals), in prison and beyond. And of course both are criminals ... Yet Montmorency changes and grows over the course of the novel, to the point where he finds himself choosing to do what's right rather than what's merely expedient, profitable or entertaining.
Very readable, nice short chapters, and plenty more in the series: recommended for children, and for adults who want a quick easy read with good pacing and quiet wit.