If you find a spare million pounds or two stuffed down the back of your sofa this weekend, you could do much worse than investing in these two exceptionally rare instruments offered for auction by Beares Auctions. Nigel Kennedy introduces the 'Cabriac' Stradivari (LOT 47, with an estimated price of $2.4m to $3.5m) and the 1782 Guadagnini (LOT 46, estimated price of $1m to $1.5m). Both videos offer a fascinating insight into the distinctly different characteristics of these violins, as well as Kennedy's discerning ear and effortless technique: