HookThames Water and what 'market' means
Thames Water serves 15 million people in London and the south-east. By 2024 it had ~£18bn of group-level debt (including parent-company liabilities; net debt ~£16bn), the regulator was warning it might collapse, and ministers had a contingency plan to take it over. Customers couldn't switch supplier — there isn't one to switch to. Prices were set by a regulator, not by competition. Investment was driven by political pressure and dividend extraction in equal measure.
None of this looks like the textbook market. And yet Thames Water sits on every UK economics syllabus as an example of "the market for water". The model is doing useful work — it tells you what's missing — but only if you remember that "market" is a spectrum, not a switch.
ModelSupply, demand, equilibrium
The standard story is the cleanest in economics. Demand slopes down: at higher prices, buyers want less. Supply slopes up: at higher prices, sellers will produce more. They meet at equilibrium price (P*) and quantity (Q*), the only point where both sides agree.
Three things happen at equilibrium, all the time, in any market: rationing (price decides who gets the scarce good), signalling (price tells producers where to put effort), and incentive (price rewards the producer who can supply at lowest cost). When critics call markets "fair" or "unfair", they're usually arguing about rationing. When they call them "efficient" or "inefficient", they're usually arguing about signalling. Keep the three apart.
ExamWhat examiners want
The trap on this topic is treating "the market" as a single thing. Edexcel mark schemes reward you for naming what kind of market is at play — regulated, competitive, monopolised — in plain terms before you start applying the model. A "Thames Water case" gets you nowhere if you analyse it like a corner-shop case.
Watch for the trade-off / opportunity cost confusion: a trade-off is the act of choosing; opportunity cost is the value of what you gave up. Examiners deliberately mark down students who blur them.