Identify breather pipe - 307 1.6 16v

[NickCUK]

I have an unknown pipe running from a T-piece where the oil breather goes into the inlet manifold. This goes down behind the engine, runs along the bulkhead and through a hole into the inner-wing/suspension turret but can't see where it goes from there.

Anyone know what this is and where it goes to?

[GiveMeABreak]

That sounds like it's the petrol vapour recirculation union, not an oil breather if this is a petrol. It carries the petrol fumes to a depollution canister and eventually returns as fuel back to the tank.