Dear shitty driver,

Mirror, signal, manoeuvre we are taught by driving instructors are we not? Not signal as you manoeuvre. What’s the point in that? I can see your car is changing direction, I can see the wheels are turning, I don't need a flashing amber light to tell me what I can already see. The moment when it would have been useful for you to start signalling was a good few seconds ago. So don’t give me that sour-faced look as I reasonably begin to nose out thinking you were heading past the junction.

I think you'll find that the useful dictionary definition in this instance is:

Signal

An event or statement that provides the impulse or occasion for something specified to happen.

See that little word ‘to’? It’s important. It refers to something that hasn’t yet happened, not that is already happening.

I’d probably rather you didn’t bother signalling at all. At least that way we can be clear that you’re just a shitty driver. Mind you, the fact you drive for a minicab firm should have forewarned me of that.