Re: @AndrueC - @Carl W - I don't personally agree but...
As has already been stated, it's clear that you don't ride a motorcycle...
> the traction engine should have been able to see me
And then, when you're lying on the ground, someone would no doubt have uttered the phrase "Sorry, Mate, I Didn't See You".
> to all intents and purposes waiting for me to go past
You assumed this. Doesn't make it a fact. If you ride a bike, you soon learn never to assume anything like that, because it doesn't make the ground hurt any less thinking "I was in the right" as you're flying through the air.
> you've suggested sounding the horn but I can hardly do that every time I approach a junction when a vehicle is waiting or I might end up being fined for excessive use
Really? "Sound your horn whenever you think another road user could hear and benefit from it" - Motorcycle Roadcraft - The Police RIder's handbook to better motorcycling.
And the Highway Code now just says not to use your horn "in an aggressive manner".
> what are you going to do here if the Range Rover starts reversing out of the drive?
Let's go back to IPSGA:
Information: There's a vehicle on the left which may reverse out. I don't know whether it's coming or going, so treat it as a potential hazard and plan accordingly. There are no on-coming vehicles. It's a National Limit, so I'll probably be doing around that limit. Check the mirrors for traffic coming up behind.
Position: As there are no oncoming vehicles, I'm most likely already positioned in "track two" (ie the line of four wheeled vehicle tyres closest to the centre line), but, absent any other vehicles, I may well consider moving across the centre line to give myself as much clearance as possible.
Speed: If that vehicle decides to start reversing out, I want to give myself as much time as possible to react and sufficient braking room, so start to slow down.
Gear: As I'm slowing down, I'd drop down the gears so I'm in one that will give good power response if needed.
Acceleration: When I get to the point that I'd have to reduce my speed much further, I'd consider accelerating and using the opposite lane in an "overtake" style manoeuvre to get past the vehicle as quickly as possible. Or, if I'm still unsure, slow right down.
All the time, I'd be updating my Information (which, of course, runs throughout the entire IPSGA system) and using the principle of TUG (Take, Use, Give) to Take information (look around, watch for the vehicles wheels starting to move, look for people getting into or out of the vehicle etc), Use (plan what I'm going to do) and finally Give: Consider sounding my horn to make them aware of my presence (and giving a friendly wave as I pass to let them know that I wasn't being aggressive).