the Eddie Dickens Trilogy.

 The Edge Chronicles

Edgar and Ellen books by Ogden.  The first title is Rare Beasts.

Among the Hidden Series by Margaret Peterson Haddix.
 

Alex Ryder series by Anthony Horowitz


The Silver Spoon of Solomon Snow by Kaye Umansky.

 a series by Deb Gliori called Pure Dead Magic

 

anything by Roald Dahl or Eva Ibbotson.