Answer: when the term is used by Nationalists. The Scottish Nationalist government is even more centrist than Labour.
Step 1 of central control: every local council in Scotland was "persuaded" not to increase council tax last April. This had an impact on education budgets across Scotland, and in places like Highland have particularly affected rural schools. This makes nonsense of their proposed Rural Schools Bill.
Step 2: introduce an extension to income tax to replace council tax (one cheer from us), but fix the rate centrally, thus denying local authorities the power to set it according to their individual needs. Call it "Local" Income Tax, in the hope of attracting naive Liberal Democrat votes.