Is the energy price cap working? Iain Conn, the chief executive of the British Gas owner, Centrica, has 300 million reasons why he thinks it has failed, as it has lopped that much off the firm’s profits. The cap, he says, is strangling competition in the market and could also strangle supply, as energy companies stop investing.

The price cap should be the ceiling for the market, but has instead become the target. Since the regulator raised the cap to £1,254 from April for the average customer, every one of the big six has hiked bills to that level, which will cost UK consumers around £1.3bn. Price “bunching” – even from the challengers – is emerging.

But let’s not worry too much about Centrica’s profits; its margins (until now) have been around 8%, an outlier among the big six, which mostly trade on around 4-5% margins.

A test of a price cap is market withdrawals: if too many providers flee, then evidently the cap is too low. The good news is while there have been rumblings, no major provider is yet heading for the exit, suggesting the cap is working.

The bad news is that Conn says British Gas has typically made around £42 to £65 profit per customer and this will plunge to around £20 next year, directly attributable to the cap. At that level, he’s adamant it will curb investment in service and innovation