That's exactly what I was hoping you'd say Pawl. And it also mirrors my experience with the previous TDV8 I had.

Sadly my pump hasn't arrived so no fun this weekend.

A thought has crossed my mind..

My last L322 tdv8 (2009, non tft dash) had the same 255 50 20 tire size as my 2010 AB but I'm sure it called for higher tire pressures? Think it was 36 psi front 42 rear or something.

The AB has adaptive dynamic suspension (or as I call it Always Damn Solid!) It calls for 33 psi front and 36 rear.

Could this account for me feeling a difference?

I might try 36 psi all round just as a test or until all my fillings have fallen out!!

Tyre pressures will have an influence on the steering effort, but you've got to be very low to have a big impact.
Very high will certainly make it lighter - but won't do the tyres any good - lol.
When I bought our car, the fronts were obviously overinflated in an attempt to mask the steering problem (that the dealer "hadn't noticed") . The tyres were at 45psi & you could see there was less in contact with the ground than intended & they wearing really oddly  Paul,
2001 Discovery 2 TD5, 211,000 miles & climbing
2006 FFRR TDV8 Vogue 145,000 miles & climbing
Member of Midland (Land) Rover Owners Club, www.mroc.co.uk

Inflated the tyres to 36 psi all round on Saturday which seemed to help free up the steering a bit more.

Got something else interesting going on now..

Drove on the motorway for 20 minutes or so, came off back into a 30mph and the steering was still weighty. It loosened up a bit after another 20 mins or so.

I left work today and the steering was feather light. I could turn it with one finger.. drove for 10 mins 20-30 mph and stopped to nip into the post office. Got back in the car and the steering assistance had decayed probably about 30 % !

Strange, not sure if this would suggest any issues with the servotronic valve. The valve looks a little weathered so could be the one from the original rack. I kind of assumed this would have been replaced along with the rack when the dealer changed it. Perhaps not.

People have previously reported Servotronic valves sticking & it's easy to imagine eg small debris particles causing is to stick & hold while either opening or closing to add or remove the additional assistance the valve provides.
You may want to try driving again with the servotronic disconnected & see if the steering "weight" becomes consistent again - even though heavier than standard.
If it does, maybe you have got an erratically operating Servotronic.
If your finding of increased assistance at higher engine rpm can also be repeated, maybe you have 2 causes of your problems. Paul,
2001 Discovery 2 TD5, 211,000 miles & climbing
2006 FFRR TDV8 Vogue 145,000 miles & climbing
Member of Midland (Land) Rover Owners Club, www.mroc.co.uk

A quick update to my moaning..

Replaced the servotronic valve and whilst doing so I was disappointed to notice the fluid was dark, no where near the colour of the new cold climate fluid and the reservoir filter was covered with bits of rubber and metal swarf.

I imagined all of this would have been cleaned and flushed with new fluid when the dealer had the new rack fitted

The servotronic and new fluid has helped a little bit but the steering is still no where near as light as it seems to be in this video:

&t=362s

Perhaps it is time for that pump i bought to get fitted..

Finally, some positive news at last!

Managed to get the second hand pump fitted today after a battle with the viscous fan.

Glorious light power steering!

Thanks for your help Pawl, wouldn't have took the plunge if it wasn't for your advice, experience and how to.

Hopefully this fix lasts more than a day.

Aagh - should hsve seen this post first!
Great news, well done! Paul,
2001 Discovery 2 TD5, 211,000 miles & climbing
2006 FFRR TDV8 Vogue 145,000 miles & climbing
Member of Midland (Land) Rover Owners Club, www.mroc.co.uk

Well, fixing one problem has led to another.

I'm getting the 'coolant level low' warning on the dash.

I bled the system following the WSM after fitting the new PS pump and I have checked the level this morning with a cold engine and its bang on the upper level of the cold marker.

I thought perhaps I hadn't put enough anti freeze in so just been out and siphoned 1 litre and replaced with concentrated OAT.

Still coming up with the warning. Any ideas Pawl?

Seems I shouldn't have joked about the fix lasting more than 1 day..

The solution was sadly short lived.

Light steering for a few days post pump replacement but I noticed it was bit firm on my way home from work Wednesday.

Dismissed it as possible low tyre pressure.

Checked pressures Thursday morning, still at 33 psi cold.

Absolutely fuming with this now. I just don't get it.

Just been for a drive in a friends 4.4 tdv8. (Not sure if a fair comparison or not) Steering nice and light... like mine was for a short while!

That's bad news .
Did you end up having a pressure test on the old pump before it was removed to confirm the pump was bad ?
Also did you get a photo of the label on the second hand replacement pump to know how old it was ?
Part of the label info gives a date code for manufacture. Paul,
2001 Discovery 2 TD5, 211,000 miles & climbing
2006 FFRR TDV8 Vogue 145,000 miles & climbing
Member of Midland (Land) Rover Owners Club, www.mroc.co.uk

I didn't have a pressure test done no as I decided it was likely to be a similar cost to just grabbing a pump and replacing it.

The replacement pump is a 2007 with 68k miles so I am told.

So far we have:
Recon rack (fitted by dealer at time of purchase)
New servotronic valve
Used pump which has done 68k
Clean reservoir
Fresh land rover cold climate fluid
Tyre pressures 33 psi set cold

I would have expected the second hand pump to be Ok if the stated milage was correct & you've said it was performing OK for at least 1 day - so it's hard to imagine the pump could have deteriorated that fast.

I think you're maybe only left with the BCU / BCM as the possible cause.
Ideally you need to bypass it and feed 12V direct to the Servotronic valve to see if you then get full assistance again.
If you do, the BCU needs replacing. If you don't you're back to questioning the servotronic valve, pump or pipes again

I ran for maybe 3 months with a direct electrical feed to the valve while I was motivating myself to replace the pump.
The least "invasive" option is to get another electrical connector for the servotronic valve - either off a scrap L322 and provide a 12v positive & negative feed to it from an ignition controlled source. Then just take off the existing electrical connector (from the BCU) & substitute the "new" one.
I found my connector on a scrap BMW 3 series - as they were easier to find. However, beware there are 3 different variants of the same size connector with different "interlocks" to prevent incorrect assembly. I think if the colour is the same as the RR one you're OK.
The more invasive option is to cut the existing wires to the valve, provide a direct feed, then re-instate the wiring after you've diagnosed the cause. I don't recommend this as the space available to work on the wiring is not great & you're introducing potential electrical failure points for the future !
The BCU doesn't get damaged by not being connected to the Servotronic valve (even if it is OK) - as when it senses no resistance from the servotronic valve it switches off that output. Paul,
2001 Discovery 2 TD5, 211,000 miles & climbing
2006 FFRR TDV8 Vogue 145,000 miles & climbing
Member of Midland (Land) Rover Owners Club, www.mroc.co.uk

I think that could be worth a try Pawl, I might see if I can bodge something together tomorrow with spade connectors just for a quick test.

Perhaps it was just in a good mood after pump replacement?

According to the 2010-2012 WSM my servotronic valve is driven by software in the CJB (central junction box) as opposed to the bcu/gem. Perhaps different to 06-09 cars? From what I can tell the CJB looks to be part of the fuse box behind the glovebox.

I remember my old 59 plate pre facelift had the option in SDD to command the servotronic valve.

I cant find the option with this car otherwise I might have been able to test that way hmm

You might find it challenging with spade connectors - the pins are really small & easily damaged (maybe 2mm wide).
Here's a photo of the connector :

Click image to enlarge

Hmm, sounds like spade connectors are unlikely to work then. I will source a connector to try this out.

Only other thought I've had is could the belt be slipping on the pump pully? I know they are tensioned automatically but perhaps if it is worn it doesn't quite get enough grip? Possibly clutching at straws with this theory.

Just been out and holding the engine at 3k rpm lightens the steering as before pump replacement. The steering seems to stay a bit lighter for a few miles after gunning the engine.

I'm hoping the used pump I fitted is actually good.. the steering was really nice on the initial test drive post fitting.

Sigh