Thanks for the explanations guys.
So if i understood correctly from the pdf link that you provided the thing in the red circle must be the "axle mounting bracket" and it indeed should be attached to the axle.
I don't know on the Megane.
The one I had was very similar to the one in the link with a lever connected via a spring to one rear wishbone. The end of the spring had broke.
Peugeot wanted summat like 90 quid for a new valve and would not supply spring on its own.
MOT inspector found it and in desperation I cable tied the spring to its mounting.... which he passed
Can't remember why I didn't or couldn't find a suitable spring but did spent some time hunting scrappers before I thought sod it. And took valve off. Not a word on next years MOT with same inspector. Never felt any issues on braking either but as it has been said, it is a safety feature.
Yours looks like it should push against the spring so may not need a connection. But you need to see how the movement of the axle operates the valve and possibly find another Meg to look under.
To satisfy your current inspector, a jubilee clip may be enough?
That we can see a little gap makes me wander if the valve has seized