Cars: An Invention

When I had a convertible, I never liked leaving it anywhere with the top down because although I'd removed everything else 'pinchable', it seemed to me that someone could take the tax disc (I'm a born worrier). Even though you can be tracked by computer now so someone else's disc isn't that useful (I'm talking about the UK here), someone could do it out of malice and losing your tax disc would still be a pain. I'm surprised nobody seems to have thought about this, or rather about ways to prevent it. First I thought of ways of sealing or screwing the disc holder onto the windscreen and making it lockable; then I thought of having a freestanding holder screwed onto the dashboard, so that the disc was an inch off the windscreen. But then it occurred to me that maybe the disc doesn't have to be ON the windscreen, just visible through it, and so manufacturers could put a circular window in the top of the dashboard, accessible from inside the glove box, and this could hold and display your tax disc. Neat, eh? Because the glove box locks, the disc would be secure. How about it, manufacturers? At least for the worriers amongst us...