The manual says to always put in gear before turning off with warning symbols used. It makes this warning two or three times but doesn't say why. Are they patronising us and protecting us from the car running away if the handbrake slips or is there another reason?

e-gear is not really an automatic, so there "is no park" per se, like in a Caddy. All maneuls, even semi-autos, like the e-gear, need to be "in gear" plus the ebrake to insure the car doesn't roll on inclines. Also, the wheels should always be turned to the curb on any steep parking situation in case the safety features fail. This is a type of blending & melding the new with the old.

Is that why I get a warning type tone when I park.

So just to confirm, I should leave the car IN GEAR, when I park.

I need to take my young GF out in you car for a week or three to know for sure!!!!

Only two seats I'm afraid.

She can come though

yes, first or reverse. It doesn't matter which.