I've no idea what chipset it uses, but thought I'd selected it from the known good hardware list on here. It certainly works with NOOBs. Perhaps that's where I've gone wrong ad I will have ordinarily avoided eBay.
As for the card, it hasn't got a slider in it (do microSD cards have those?) The adapter does have a slider... sliding it makes no discernible difference. I've googled a fair bit and it's clear I'm not the only one with this issue related to SD cards, but non of the proposed solutions works.
Are some SD cards single write only? In fact this can't be true of this card because I added the PAW files, booted the pi and now there are two partitions so it's clearly been written to twice!