By Guy Taylor National Express owner Mobico has announced the departure of its chief financial officer after accounting issues caused the firm to delay publication of its full-year results twice. James Stamp will stand down at the group’s annual general meeting on 11 June. Helen Cowling, a veteran CFO with experience at Octopus, Selecta Group and Ideal Standard International BV, will fill the role of interim CFO on the same date. Mobico had expected to report its full-year financial results on February 29. However, audit issues at its German rail business caused by changes to indices used by t…