Inflating your stock price by buybacks is easier said than done.

In fact according to the CAPM economic model, it is impossible. The assets of the company decrease by the money spent on buybacks, which matches the value of stock bought and destroyed. This should leave the price per remaining stock unchanged.

Sounds to me like the CAPM economic model is in need of revision. Buybacks are a common tool for increasing shareholder value and investor sentiment figures heavily in asset pricing.

There are a number of reasons why buybacks can increase prices. See https://www.mckinsey.com/business-functions/strategy-and-cor... for a list.

All are second order effects.

Ok as a general point, but those criticisms simply do not apply to Cooke. The company has done absolute gang busters both in products and fundamental performance, and that's what has driven up the stock price.