When the chief executive of AXA Insurance decided in 1995 to start a corporate art collection, he asked the Dublin artist Bernadette Madden to organise it. Her starting budget was IR£5,000 a year, a modest amount, but she was determined to show that an art collection could be built up gradually while spending very little money. Madden sourced works directly from artists, or from their galleries – never from auction houses. She went to graduate shows, a great place to get work by a star of the future at a modest price. A few years later AXA considered moving to…