Professor McIntosh has made outstanding contributions in the areas of functional analysis, harmonic analysis and partial differential equations. In recent years he has achieved considerable international fame through his resolution with Coifman and Meyer of the L2 boundedness of the Cauchy integral on Lipschitz curves. The latter work, which was listed in a report to the American Mathematical Society among three "recent dramatic examples" of "progress in theoretical mathematics", has itself spawned a great deal of contemporary research by McIntosh and other leading mathematicians.