Colin Gleadell digs deep into this notebook for some serious art market score-keeping on the London Contemporary sales and shows that the most astute players were the biggest winners this time around:

• American collector, Kent Logan bought Ron Mueck’s lifelike ‘Man Under a Cardigan’ for less than £20,000 in 1998, and it sold for £600,000. He also bought a painting after Fragonard by Glenn Brown for $175,000 at the Frieze Art Fair in 2004. That sold now for £937,000 or $1.5 million.
• On an annual percentage basis, however, Logan was probably pipped by Charles Saatchi who had acquired a robot shaped abstract painting by young American artist Joe Bradley in 2006, when his prices were around £4,000. Five years later, and a Whitney Biennale show under his belt, the Bradley sold for £79,000. In 2008, Saatchi bought several paintings by the US based Iraqi painter, Ahmed Alsoudani, for around £20,000 each. Last week, one of them sold for £713,000.