I think you are correct. There is a huge difference. If your relatives didn't own anything worth declaring to the lawyers, or the HMRC and no probate schedule, then you have no evidence of inheriting this stuff. Your cost of sales is zero - same as if you found something in a charity shop and they gave it to you for free and then you decided to sell it. You have then taken this stuff and decided to sell it. That is a business.

If the value is low - a few hundred items a year, then there may be no tax payable of course. But if say you were `also claiming benefits, or had a job, then tax may well be due. Not to mention NI. This would be what they are calling side hustles right now, and they are cracking down on.

Under normal circumstance, I would agree with you, HMRC will not want to know. However, looking into the not too distant future, I dont think it will take the AI long to run through the entire eBay website cross checking details and sending out intitial assessments. At that point, it is up to you to prove them wrong on paper.

To stay on topic, I dont think eBay is dead, but I do think there is a big clean up underway and I personally think there will be a lot of money raised this way for our common tax pot. People who previously had justified their own actions in their own heads, may well wake up to find an alternative reality. I would simply say get your self assessment in, then you will have no problem.