George Cruikshank introduced him to the caricaturist John Leech .
George Cruikshank is the illustrator who had previously worked with Dickens on Sketches by Boz ( 1836 ) and Oliver Twist ( 1838 ) .
George Cruikshank , the illustrator who had previously worked with Dickens on Sketches by Boz ( 1836 ) and Oliver Twist ( 1838 ) , introduced him to the caricaturist John Leech .