Pablo Picasso’s 1941 watercolour Tête de femme, valued at €1m, on display at Christie’s auction house in Paris. enoît Tessier/ReutersPablo Picasso’s 1941 watercolour Tête de femme, valued at €1m, on display at Christie’s auction house in Paris. enoît Tessier/Reuters€1m Picasso portrait up for grabs for €100 in charity auctionArtwork by one of the most influential artists of 20th century raffled to fund Alzheimer’s researchHis work is consistently ranked among the world’s most expensive art, with paintings fetching more than a $100m at auction.