Indeed, I wonder if you can quantify in cash terms the value of "Public services run by people who feel there work is valued" as an investment?

Damnit. *Their

Yes, easily. If public sector workers costing £60k to employ are leaving and have to be backfilled by private sector staff who cost £200k+ to employ (plenty of examples) giving the perm staff a pay rise can pay for itself quickly if the accounting allows it