“This investment reflects Sports Direct’s growing relationship with Tesco and belief in Tesco’s long-term future.”

The first half of this explanation for why Sports Direct is betting that Tesco’s shares will rise makes no sense. There is absolutely no need to “reflect” a trading relationship in this way. Even if there were, the natural method would be to buy shares directly and hold them loyally.

Instead Sports Direct has entered a put-option agreement with Goldman Sachs that necessarily has a fixed expiry date. When the bet is settled – shareholders are not told when – Sports Direct’s commercial relationship with Tesco, which amounts to a few shops-within-shops, won’t change one jot. Tesco’s board couldn’t give a damn if Mike Ashley’s outfit wins or loses its bet, or even if it ends up owning 0.28% of the supermarket chain’s equity.

This, then, is a straightforward punt, dressed up as a “belief in Tesco’s long-term future”. Yes, there’s an argument that Tesco’s shares – despite the accounting debacle, 75% dividend cut and falling profitability – represent decent value at half the price they were a year ago. But Mike Ashley’s punting record doesn’t inspire confidence: he lost a large sum (even for him) gambling on a recovery at the doomed HBOS.

At HBOS he was risking his own money. Fair enough. But the Tesco adventure is through Sports Direct. Ashley owns 58% of the company, but that doesn’t give him the right to use the business as a vehicle for speculation. The outside shareholders, led by hedge fund Odey (with 8%) and asset manager BlackRock (5%), are quite capable of forming their own opinions about the direction of Tesco’s shares which, incidentally, BlackRock has been selling.

Sports Direct investors, it might be argued, know these sorts of adventures come with the territory; in January, it was Debenhams, again via an option bet with Goldman Sachs. And £43m, Sports Direct’s maximum theoretical exposure on the Tesco option, is not a life-changing sum for a company worth almost £4bn.

But what’s the limit on these gambles? Is there any level at which the supine non-executive directors would tell Ashley to use his own cash if he fancies a flutter?