Quick interesting one.

Firstly am I correct in assuming that the 5.0sc has a 101 litre fuel tank? Thats what the manual says,

As on mine I always run from full to red light warning, however in the few months I have had this one never get more than 80 litres at the pump. On my previous 4.2sc the light came on with about 10 litres in the tank.

Is there a calibration rest on the sender does anyone know?

I would suggest that you always keep the fuel gauge at least 1/4 full, if only for the fuel pump(s)

In order to function properly, it needs to be completely submerged in fuel. Typically, this means you need at least ¼ of a tank to keep it submerged.

Long-term exposure to air can lead to early deterioration of the fuel pump.

Leaving it constantly exposed to air can cause the pump to suck in air and generate heat. This can reduce the working life of your fuel pump significantly.

Allowing your tank to run low can also make room for sediment to build up in your tank.

Thanks for the info sounds sensible, I guess I am doing that as I only ever get 80 litres in a 101 litre tank so it always has 20% fuel in it, maybe that's why the light comes on at that point in my 2011 and it came on at a lower level in my 2007 that I had before, maybe landcover were seeing pump issues and changed it.

This is from the L322 workshop Manual for the V8.

Fuel Delivery System Components
The Land Rover V8 fuel delivery system comprises the following main components:
l Saddle type fuel tank
l Fuel injectors
l Non return fuel rail
l Fuel pump
l On board refuelling vapour recovery system (NAS only)
l Tank leakage detection system (NAS only).

Fuel Tank
The fuel tank is constructed from moulded plastic and is mounted under the rear seat just forward of the rear axle.
The fuel tank has a 100 Litre capacity and activates a low fuel warning lamp in the instrument pack when there is 12
litres in the tank. The tank is of the saddle tank design with a siphon jet pump in the left side to transfer fuel to the right
side where the fuel pump is mounted. The fuel is delivered along pipes that run along the underside of the vehicle to
a fuel rail mounted on the engine.

And that is exactly what happened on my 2007 4.2sc, but the light comes on and I drive a little bit more maybe 20 miles and still only get 80 litres at the pump, so I guess the 2011 model wither the light comes on with more fuel nth tank or my sender is faulty.

also remember Lighthouse, your newer 5.0 is now direct injected more like a diesel so......... DO NOT run it out of fuel... Its not a straight forward refuel, crank and away you go... The fuel pumps go into a safe mode and diagnostics are needed to reprise the system etc etc...

Not intending on running out, but 20 litres in the tank is 60 miles in range takes the beast to over 300 mile between refills if you can use it all.