Was poking around the engine bay and found this hose just lying up near the firewall on the driver's side. Neither end was connected to anything and despite several minutes of searching, didn't find anything obviously missing it's hose.

 

I'm guessing it's one of the hoses to the distributor vent system

https://parts.jaguarlandroverclassic.../brand/jaguar/

https://parts.jaguarlandroverclassic.../brand/jaguar/

Cheers
DD

 

My guess is cruise control. That white piece looks like a broken “T” fitting

 

I think Doug is correct. It looks like the plastic piece is the one that joins the top dizzy vent hose to the AAV/manifold hose, its barbed bit having mostly broken off. No 6 in this diagram Doug posted;
https://parts.jaguarlandroverclassic.../brand/jaguar/

 

Yeah, I had the AAV off recently - that looks like the distributor cap vent. That white right angled fitting is broken off, & is the one mounted on top of the large AAV > airbox hose.

 

IF it is a Marelli, it isn't part of the dizzy vent system, as the connector on the AAV hose take off is brass. The hose routes then to another metal fitting on the dizzy. The other side is from the wing to the dizzy. In the wing is a plastic air filter. Again, no 90° fitting...

EDIT:

seems the brass fitting isn't standard then...

 

Thanks a bunch, guys. It gives me a starting point to chase down. I also have an air filter, contacted to a longer hose that goes nowhere which looks suspiciously like the one in the first link Doug posted.

 

Yeah, that little filter (looks like a cheap fuel filter you get on eBay) goes on the end of the other distributor vent hose, & just sort of dangles where the cross brace connects to the inner wing.

 

Yeah, that sounds about right. Kind of a cheesy implementation. I'll have to see if I can come up with something a little neater.