Fuel leak - only on a full tank!

[BikeBoy]

I have a 2008 Freelander 2 SE i6 - when you fill the tank until the bowser auto cut-out kicks in, and especially on a hotter day like today (reaching mid 30's), fuel will dribble out from somewhere up under the rear left wheel arch, and out onto the ground from the panel of the wheel arch at the back near the back bumper, right next to the left hand exhaust.

Is this a 'normal' overflow valve thing? Or do I have a leak there somewhere that needs attention?

I tried searching for information and so far have come up with nothing.

I usually try not to fill the tank completely and this never happens, but I overestimated again filling up today and I can smell the fuel as I type.

As far as I am aware the fuel pump is on the other side, accessible from a cover under the rear right passenger seat.

So what is happening on the left at the back that could be leaking like this? If not by design..?

Any input appreciated.

[woko]

It has a leak. Tanks don't vent out. It will have a evaporative emissions system that burns it off through the engine.
There will be a leak in the fill breather that goes from the top of the left side of the tank to the top of the filler neck

[Didge]

my defender leaks at top of tank where return fuel line connects and like yours, only when full