Was back on the ramp today and this is the verdict

The knocking sound is the arm that has play. Reason it wasn't noticeable before is because the arc system wasn't operating hence the intermittent suspension warning light.
Now that has been fixed by replacing the shut off valve, the arc system is operating and exposing the issue with lower arm.

Sorry if that doesn't make sense, trying to relay the mechanic's answer 07 TDV8 + BAS map

That sounds plausible. So it sounds like the active system was disabled to disguise the fault, is that what they are saying? 2x TDV6. SE and HSE. Both returned to sender with issues👀
TDV8 Sport HSE...... Gone. Loved it but it didn't love me!!
Now rolling in MY10 Fullfat TDV8 Vogue. Slammed it to go round corners🙈
Cruising daily #56 mph in a Volvo V8. 😱
Lots of other toys in the cupboard...😜

Yes.

THe hissing sound I mentioned is in in fact rust on the front discs and despite they not being end of life, they recommend replacing disc and pads replaced. Isn't that hammer to walnut approach? 07 TDV8 + BAS map

Updated the original post with the outcome of this 07 TDV8 + BAS map

Result although you should not have had to resort to this. I hope the dealer gets a visit from Trading Standards too. Interesting to know who the warranty was with, a company or the seller? 2x TDV6. SE and HSE. Both returned to sender with issues👀
TDV8 Sport HSE...... Gone. Loved it but it didn't love me!!
Now rolling in MY10 Fullfat TDV8 Vogue. Slammed it to go round corners🙈
Cruising daily #56 mph in a Volvo V8. 😱
Lots of other toys in the cupboard...😜

A warranty 2000 jobby sold with the car.
I took out my own with warranty direct who have been good so far with works done at main dealer. 07 TDV8 + BAS map