It is a question that Sylvette, now 63, has pondered often, just as she has cursed many times that she never modelled in the nude for Picasso even though he suggested it to her. "One day, after I had sat for him some days, he produced a drawing of me naked and said: `I hope you don't mind, but I was intrigued and used my imagination'."
Sylvette, who changed her name to Lydia to escape the connection with Picasso's muse, is sitting at the kitchen table of the small house in Devon where she spends several months of the year - the others are spent in her native France - surrounded by Picasso prints (she sold the original he gave her as payment for modelling) and her own paintings and ceramics. She is a handsome woman who wears her fair hair long, and her girlish expression is recognisable in the first gentle, naturalistic drawings Picasso did of her and even in the Cubist interpretation of Sylvette in a Green Armchair.
She clearly enjoys the opportunity to tell a story which, you sense, she has taken out, polished and delighted in many times since that one summer when a man old enough to be her grandfather had his eye on her. "Picasso didn't analyse my appeal as a woman in words, although he did say several times that he liked my head, my neck and my hair, and he was fascinated by my ponytail."
He made it plain that he wanted to paint Sylvette when he popped over the wall one day with a sketch he had done of her, remembered from the brief occasion when she had met him. "My friend, more beautiful than me, asked if he would draw her too, and he was angry. His black eyes flashed and he said: `I only do those I like to do'."
Picasso had just separated from Francoise Gilot, who was living in Paris with their two children, Claude and Paloma, and he had not yet got together with the divorcee Jacqueline Roque. It was a time that he described to Sylvette as "very troubled, very painful" on several of the occasions she posed for his 39 pictures of her, and he "thanked me for being sweet and peaceful".
"I was so innocent and such a prude," she says with a giggle. Not the way women tended to be once they were caught up in Picasso's desires. Arianna Stassinopoulos Huffington, in her book Picasso: Creator and Destroyer, described how the artist's last wife shot herself, one mistress became insane and another hanged herself.
Corbett (her married name) shrugs angrily: "This was not the man I knew. Picasso was courteous and sensitive to my feelings. He was quite beautiful and smelt nice - not of cigarettes or anything. And with me he seemed to find it easy to be playful. Quite often he would clown around like a little boy. I was fascinated to see such a lively old man. I loved Picasso. I still love him. I think about him every day."
It is legendary that Picasso's models had affairs with him but Corbett fixes me with a very serious look: "My claim to fame - I did not sleep with Picasso [although Francoise Gilot wrote that she was convinced Picasso used Sylvette to make her jealous]. Do I regret that? I am not saying so, but I do sometimes wish I had been less of a prude at the time."
He was probably propositioning her the day he took her on a tour of his house, through the many rooms of the pottery, into the little white-washed attic room with a table, chair and his bed. "He jumped on the bed and began bouncing up and down, laughing. I remember thinking, perhaps he wants me to play games like naughty children. But I didn't. And on another occasion he took me into a barn where he kept his car, an old Hispano Suiza, and we sat on the back seat like a couple going on holiday, chatting and laughing, and I wondered what he was about. I kept an eye on him - was he playing a game to see if I would fall in his arms? But I didn't."
All this is told with laughter, but in a quite dramatic change of mood she tells how Picasso was "like a godfather to me".
She sheds sudden tears, wiped hastily away, as she describes how he asked whether she had seen her father recently: "I said I hadn't seen him for 10 years. He did not live with my mother and he never brought me up, though he found me more interesting once I was modelling for the famous artist. Then Picasso told me he had had a letter from my father asking for one of his pictures of me. Picasso tore the letter up there and then. It was sweet and very protective of him."
Then the summer of 1954 ended. Sylvette left Vallauris and later came to Britain. She had two marriages which have both ended. She began painting 20 years ago, when her three children were grown up and since then she has had several exhibitions of her work. Her paintings came first; the ceramics followed.
So was it Picasso who inspired her to become an artist? "He said there was nothing like art to be happy, and he taught me how it was possible to see a subject in different ways, how to have fun with colour. It is wonderful to have been touched by Picasso, but also to feel I touched him."
Lydia Corbett's ceramics are on show at the Francis Kyle Gallery, Maddox Street, London W1