You seem quite intent on doubling down
I presume you mean that I am continuing to state the situation as I see it. I find it weird that people think you can take.advantage of others when they make honest mistakes. I think people are better than that.
The distance selling regulations are not really relevant here. Nobody on this thread is disputing that OP had the right to cancel the order at anytime.
Yes, the goods may have been consumed depriving Tesco of the opportunity to recover them, but that doesn't automatically mean a payment is needed.
No it doesn't immediately, but intent is important here which is why I've used the wallet analogy (theft by finding) previously. If you fail to make any attempt to inform the retailer and you also permanently deprive the retailer of they goods they still own, and you make use of the windfall, then you either fall under the theft act, or you have become party to an implicit contract. (The delivery is construed as the offer, the consumption as the acceptance, and the groceries and previously quoted ££s as the consideration)
Tesco are responsible for recovering the goods at their own cost
That's 100% true. The law has provided an acceptable remedy to Tesco, accepting that mistakes are.inevitable.
But as you have agreed, the OP denies them this opportunity for redress by consuming it all and it is this action which makes them liable. For example, if someone transfers £10000 into your account accidentally they are entitled to have it back. It is not a defense to say "sorry, I spent it all" and similarly it is not a defense to say "we ate it all"
I can't see Tesco losing sleep over £300
Neither can I. And I think the OP is foolish not to just tell them and likely have it comp'd and avoid all the angst. But what if the order had been £300,000 instead. Would you be making the de.minimis argument?
But the value doesn't change the law and it shouldn't affect our moral need to comply with the law. Similarly the fact that this is Tesco rather than a small business changes nothing either from a legal or moral standpoint.
From a POV of simple human decency in In layman's terms..., if you don't.like the steak send it back, don't eat it all and then ask for your money back.