I've been suited up like a chemical worker trying to etch that bloomin' lino and guess what? Not a mark on the darned stuff! And that's despite checking my methodology with Lesley Trussler's detailed instructions. So on further examination I can conclude only that what I'm using isn't actually the real thing - it's an imposter masquerading as lino!
Back to square one: first, acquire real lino; second, start all over again.
I'm admiring the day outside instead of feeling frustrated