I first met Judith years ago at a Christmas party in a tiny illustration gallery packed to squashing point. I thought she might have had enough of talking to strangers – everyone wanted to meet her – so I decided not to bother her by saying hello. I was wrong about that: Judith liked meeting people. She was charming and funny and, mercifully, even though it was a small talk sort of event, she wasn’t a small talk sort of person.

If I could sum Judith up in just one anecdote it would be this one. She was telling me about a family photograph. Her parents are standing looking quite serious, four-year-old Judith and her brother, Michael, are both sitting on tricycles.

“I remember feeling very proud and pleased because I had just learned to ride a tricycle and now here I was having my photograph taken. When I looked into the camera I was wondering to myself: ‘Do I look like someone who can ride a tricycle?’”

I marvel at this tiny child willing her expression to communicate something so abstract, imagining it actually might be possible for someone to one day look into this photograph and see something in that child’s face that tells you, she is a girl who can ride a tricycle. She is not thinking: “Is the tricycle the clue?” but rather “Is it the expression on my face that gives it away?”

And here is Judith aged four thinking exactly like an illustrator. Judith could not only recall these moments huge and minuscule, but she could take you with her, lead you right into that memory as if you were there in the first place, discussing it back and forth, making it a conversation, a shared thing.

When she told the story of the tricycle (and I made her tell it more than a few times) her face would light up, full of wonder at the sophisticated thinking of the child she once was – not ever believing it peculiar to her but understanding that all children have such sophisticated thoughts.

When grown up, we are inclined to forget how interestingly our minds once knitted ideas together; we tend to walk past the seemingly ordinary details that used to intrigue us. But Judith did not forget, she valued it all and continued to observe those small close-up things which really explain who we are.

Several years ago, when we went to tea with Judith, my daughter, then aged four, whispered very loudly in my ear: “I want to see Judith’s bedroom.” Judith immediately got up from the table and said: “But of course you do.”

Because why would you not want to see? For the bedroom, the kitchen, the whole house (which we were shown) tells you a lot about the person who lives there – why not understand your host better by looking at her things? And why not understand your small guest better by watching to see what catches her eye?

It is this way of thinking, this way of looking, that made Judith such an exquisite illustrator and writer and such a fascinating person to know. She never forgot to be curious and she never failed to delight in someone else’s curiosity. And this of course is what keeps you young. And Judith was ever young.

I will miss those conversations, always interesting and above all, always funny. She rang me once to tell me she was to have a cataract operation, only she said: “I keep getting the word mixed up and wanting to say cormorants.”

We would chat about our work. Occasionally she’d tell me about a piece of writing she was struggling with, never pretending things came easily: “Oh I find the writing so hard, how do you do it?” There was never any suggestion that she was somehow on a different plane from me. We would talk about friends and work and things going on in the world, or a new eraser she had recently purchased. And of course the evening that we met David Beckham and his family at her favourite local restaurant, and he was so delighted to meet her he had paid for all our dinners.

“Wasn’t that fun?” she said, when we got back to her house, laughing and sipping our large tumblers of whisky. Time had fallen away, and she was giggling as if she were no more than 20, and suddenly we were all 20 again – just back from a really good night out, one of those nights you just don’t want to end.