The Kensington Reptilarium — N.J. Gemmell

The Caddy kids are home alone, having the best time ever -- until a stranger arrives with news. This is the story of how four loud, grubby urchins from the Australian outback find themselves in London for the first peacetime Christmas after years of war. Their new guardian hates children, preferring the company of the hundreds of snakes in his house -- the Kensington Reptilarium. Fate lends Kick, Scruff, Bert, and Pin a helping hand when outraged citizens call for the Reptilarium to be shut down. With the police about to descend, can the kids warm Uncle Basti's heart before it's too late?