I am very reluctant to purchase any battery on here. comments welcome
There are some things it makes sense to buy on eBay. There are others in which the risks outweigh the attractions. I think that aftermarket batteries, almost universally from China, are definitely among the latter.
From questions received here over the years we have repeatedly heard of problems ranging from poor performance and short working life to serious safety issues and batteries catching fire. Items made in China don't have to and often don't comply with UK safety standards, even if marked as doing so. Consumer safety organisations have repeatedly issued warnings about the risks of buying imported batteries from "online sales sites." The airlines have even voiced concerns about the riska of fire from unsafe aftermarket batteries in phones and laptops.
Keep in mind that eBay specifically warns buyers that they do not guarantee the quality of items, or even rhat they will be safe or legal. Would you have bought from a shop that stated this?