I shouldn't have to say it, but I will. (Still with the tiger in The Tiger who came to tea'.)
If it were 'just a tiger', then we would want it to behave according to what we know tigers do. In our collective experience and knowledge of tigers, a tiger that turned up at a house would in a British context (as is the book according to its signposting in the illustrations) be an escaped tiger. It would be fearful and dangerous to humans.
So this is a 'book tiger', not a tiger…the kind of tiger that it's OK to find in art and literature. Surrealist if you like. So, that's yet another reason why we can ask, 'what does this tiger represent?' We can speculate about what it might represent for Judith Kerr….and we can investigate ourselves to discuss and wonder what it might mean to us and to our children. Two separate things that may or may not overlap. And whatever it means to Judith, may or may not have bearing on what we make of it. That's up to us to decide. And there'll always be more meanings beyond whatever we say anyway…The meaning bag never fills up!