It was Millais. He was the youngest entrant (14 yrs old, I think) and, subsequently, the youngest graduate of the Royal Academy in Britain at the age of 19 years. Amazing, really.
Brian,
The signature in the painting in question is probably Picasso's written as "P. Ruiz y Picasso" which was his original name; the "P" standing for "Pablo", of course. Later he adopted simply the "Picasso" moniker -- which itself is his mother's maiden name.
His father was an academy art teacher, and, apparently a good one. Picasso clearly had a lot of exposure, guidance, and training in art since a very early age, so it's no wonder that he was precocious. But -- returning to Millais for a moment -- precocity at an early age does not mean one will become a great artist. What I mean is that, yes, Millais was truly one of the great 19th century painters, but he isn't normally listed in the pantheon of the all-time gods of art, as Picasso is. Yet, Millais was every bit as good or better than Picasso at even a younger age. In fact, he created multi-figure history paintings at age 16, which are very impressive (the cover of the book "Guns, Germs, and Steel" has one of these reproduced on it).
There have been artists in the past, as there are today, who are fantastic at a young age. But, they aren't all thought of as being the "greatest ever". Yet Picasso, obviously on account of the work which made him famous, has his early stuff elevated to a ridiculously high level. It's good, yes, but it's no better than that of many before him could have done. The hyperbole surrounding Picasso's early pictures largely arises because so many who came after him couldn't aspire to his level. Yet, prior to Picasso's time, there were surely many artists, both known and unknown to us now, who showed enormous potential at an early age, yet we don't elevate them to deities. Funny.
The "Picasso is the greatest; just look at his early work" school of thought is nothing more than another 20th century bias toward Modernism. Understandable, perhaps, but a bias nevertheless.
Juan
--
The Fine Art of Juan Carlos Martinez is at: