Unions can no longer ignore the fact that managers "are not the authors of the pretty unforgiving arithmetic", Mr Angus writes.
Less management in colleges would not produce more money, he adds. In a defence of the much-criticised managerial approach in colleges since incorporation five years ago, he states: "The notion that public cash does not need managing - only the application of professionalism and goodwill - is attractive, but badly wrong."
Mr Angus says that if the Government remains determined not to increase the money available for FE unions and management will have to sort out their relationship. "Taking pot-shots at college managers, individually or as a group, may be easy because the managers have little effective right of reply, but that is no substitute for grappling with necessities like changes to conditions of service."
Mr Angus's plea coincides with the report by Helena Kennedy's committee (page 26) arguing for a redistribution of investment towards FE, but he points out that "one more pound to further education is a pound less for the Health Service or hard-pressed schools or other public spending priorities".
"Only the foolhardy" would suggest that there is no room for higher productivity in many colleges, Aberdeen's principal states. Differences in costs are not simply due to "remoteness" or "special circumstances": they reflect differences in efficiency.
Mr Angus wants a new strategy for FE with a balance between co-operation and competition.