Where to point the aerial on 2.4

As Dean said. It doesn't make any difference whether the aerial points straight down, or straight up, when you hold your transmitter in your flying position.
The easiest way to picture it is to imagine a ring doughnut with a stick poked through the hole.
The stick is your aerial, and the doughnut is where the signal goes - nothing from either end, and most of it out sideways - in all directions sideways!!

The same applies at the model end of things, which is why they give you two aerials, to be positioned at 90 to each other, that way, no matter what orientation the model, one or other of the receiver aerials is sideways on to the transmitter aerial.

You can have your transmitter aerial pointing sideways, if you wish (some now are built into the handle) BUT if you are flying, with the model in front of you (how else?), and turn sideways to speak to your pal, you present 'the end of the stick' to your model, and - whoops - lost it!

Garry, you've said yourself that there is often nobody else there, so you aren't going to turn to your left to talk to someone!
With the aerial lying on it's side, you are still 'showing' the model the side of it, not the end, so what I put stands.
It's of no importance, but some of your transmitted signal goes straight up above your head, into outer space, and some of it goes straight down into the ground, but as long as the model is in front of you, that's ok.

Just a side comment - As I had full control of my model at 1585 feet range, I must be doing something right (but not in the eyes of the BMFA!)
Well, my excuse is - I didn't know how high it was until it came down!

Duh! I don't know why I never thought of that BB, I thought everybody knew!

Up, down, doesn't make much difference. Remember the 'doughnut!' Only the angled 90 cm bit on the end is aerial. The rest is just a spacer. As long as your transmitter aerial is vertical relative to ground, when you hold your transmitter in your flying position, you get the best radiation pattern.
I'll not post this any more, as the argument is going round in circles.