The instructions provided with the test were quite specific. Courier knocks, steps back 2m. You put out your test in his box. He picks it up and takes it away. Simple. Except that's not how it happened.
He knocked, stepped back a meter, passed me a label to stick on my box, I had to take it out of his hand, stick it on the box myself, then put my box into his box. He didn't have gloves, he didn't have a mask.
So I rang them up and asked how it's supposed to work, apparently he's supposed to put the labels on himself.
The test period is drawing to a close, but this is just a warning for anyone else who's involved in this. Get the courier to stick the label on himself. He's been told by the testing company to do this. Don't take any BS, and stay safe!