The willingness of top City firms to act against investment banks looks set to come under the microscope after the Co-op pension fund last week sacked its former fund manager Merrill Lynch in preparation for an expected legal challenge.

As reported by Legal Week in March, the Co-op has turned to Richards Butler to handle the case, which relates to alleged mis-management by Merrills’ UK asset management arm, after being turned down by at least one leading City firm which was unwilling to act against the bank.