They're definitely the old hoses, so I would check those first. The split(s) can be very difficult to spot, have a look for any soot or gunk around them. Having looked at the photo, is there any gunk / soot around the RHS Rear Hose? It's difficult to tell on the photo, but it looks like that may be where the problem lies.
As mentioned, you can either get the LR upgraded hoses (quite expensive!) or you can get some silicone hose and make them up yourself.
Do a search for the long 'Restricted Performance' thread on this forum, gives you all the necessary info for the replacement hoses.

Amazing thanks - i’ll pull them off tomorrow, measure and make up
Some hoses. Hopefully thats where the issue is.

One had a small clip on the edge of where the hose clamp is… very much hoping thats my problem! I’ll measure up for silicone ones now. Wouln’t have thought that would cause a leak where it is though…. Hopefully it has.

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Worth changing them but it shouldn't leak from there as it's on the outside of the clamp. 2012 TDV8 Vogue (L322)

Rubbish - that was my thinking. I’ll swap them anyway.

Anything else to check while its apart before i put it back together. New hoses coming tomorrow.

I would give the plenum and MAF sensors a good clean before putting everything back together. Maybe check the plenum for any signs of a split.
That split doesn't look like it could be the cause of the fault, where did it come off on the Plenum, i.e. front left, rear left, front right, rear right?
There's also the possibility that the jubilee clip had loosened ever so slightly due to the split, looks like something has been cutting into it.
Keep us updated.

EDIT: Is there a residue of oil or soot around the split section of hose? It's hard to tell from the picture whether there's anything around where the split is or if it's just oil, etc. that's come from your hands.

Hard to say there was so much mess oily residue around/in the plenum anyway. I thought there might be some soot but minimal.
I’ll clean all the sensors tomorrow when the hoses come, put it back together and see where we are.

Any black oily stuff outside the plenum means you have a leak. The throttle body to intake seal sometimes leaks as well and it's a push fit and lip seal with a retaining clip so not as secure as the intake to plenum connectors. 2012 TDV8 Vogue (L322)

Thats probably the muckiest bit to be honest at the front, rest not to bad so that might be a favourite, the seal point in a little and is grubby - i assume its worth changing if i can find a part number. I’ll clean it all up, change the hoses for silicone hoses as well and see where we are - just waiting on hoses now.

Just cleaning the donut whilst its off…

The 4 holes don't look the most round…..

One connection was a little muckier than the other 3 but not bad really. The oily horrible bit was around the egr and throttle body especially underneath which i’ve pic’d below.

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Cleaned it all out, 4 new hoses etc… etc…. Still going into restricted the 2nd or 3rd time you push the throttle hard on a drive. No change.
Really don’t like admitting defeat, but it Looks like i’d better let a grown up at a specialist look at it

I’ll read the codes tomorrow when i get my scanner back and see if the codes are still the same.

CSOV check next
Also high pressure smoke test for intake leaks. Inlet manifold can split on these Gone to a good home: 2011 4.4 TDV8 Vogue SE Buckingham Blue with Ivory and clear glass = "Rory"
2025MY Defender D350 90 in Silicon Silver on coils
1974 Series 3 Lightweight = "Millie"
Many, many other Landies over the years
My preferred specialist: www.glenrands.co.uk
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If the csov is the changeover valve… i reached it and can opening it squeezing with my fingers… no bolt on top so its the revised one… moving eith hands doesn’t mean its working i suppose

Codes are still as follows….

Intermittent - p040D-00 - egr temp sensor a curcuit high

Intermittent - p004c-77 - turbo boost control solenoid B circuit low

Intermittent - p004B-71 - turbo boost control solenoid b circuit range/performance.

Turbo b is the big one i assume - so its got to be something to do with the valve or actuator? But the valve is definitely the revised part.

I had that code it is the solenoid to the second turbo, I Changed it out and it has made a big difference to the pickup.
When I tested the solenoid by putting 12v across the terminals it worked intermittently and kept sticking? my understanding of how it works ( subject to correction ) is that when pressure builds up in the chamber it pushes up the plunger which activates the solenoid which then causes a vacuum which opens the wastegate that spins the turbo I think??
Anyway, the car was okay to drive as long as I kept the revs down if not it would go into a restricted performance which I could clear with my IID tool.