It\’s often difficult to tell which is which, for the behaviour of firms in either will often be the same.
The Cartel Office found no evidence of deliberate collusion but said the companies were quickly following each other in raising prices above the level they should be.
Everyone raising their prices at the same time would be what you would indeed expect from an oligopoly.
But it\’s also what you would expect in a completely free market. So the evidence that everyone is moving prices in concert doesn\’t actually tell you that they are acting in concert.