From Prof Tim Congdon.

Sir, John Kay (“How we let down the diligent folk at the Halifax”, September 24) is too well-disposed towards marriages of retail and investment banking, now celebrated in the US and elsewhere in “bank holding companies”. The trouble is far worse than an incompatibility between two cultures. More serious are the numerous conflicts of interest, and the severe agency problems, that riddle bank holding companies. The conflicts have been exacerbated when these companies include fund management operations as well as banking businesses, as has recently been the fashion.