The biggest note in the UK is the £50 note. In my entire life I have handled one three times. Each time not a single business would accept them and I had to go to a bank to deposit it instead. Looks like it's a voluntary ban to me.
Maybe you're not British. I'm not, and British weather is doing all it can to prevent me from spending time in the UK, and yet, I have more experience with £50 notes than you have. I haven't used a credit card this week, nor the week before.
Yes, there's a war on cash, and I'm proud to be in the resistance. I once had 8 1,000 CHF notes in my hand (only for a few minutes, though), and let me tell you something: it's a really great feeling.