Thanks for the info, I'd taken care that it didn't fall out when I had the strut out by sticking a big (#3 philips) screwdriver through the lower wishbone hole (where the lower balljoint bolts in) and wiring the driveshaft end that used to sit in the hub to the screwdriver handle with some spare zinc coated garden wire.
The whining was constant and worse on one direction of corner (can't recall which), so I was reasonably confident of a wheel bearing going.
I wanted to replace the bent 'swivel pin' castings anyway (that needed 1mm washers between hub and caliper carrier to stop the calipers touching the discs since the last wheel bearing change by a garage) and wanted new top bearings in there so the whining sound was just a prompt to get on with the mini-overhaul.
Got the swivel pins from eBay at a good price and they fitted pretty well, the only difference is the square pinch bolt head needs a spanner now as the grinding on the new one no longer locks the heads - but that's a small detail, everything else bolted right on - parts 364642 and 364742 FYI.
At least it's nice and straight now LOL and I know all the nuts turn. Brakes feel good too as everything is now straight.
As an aside I also freed up the pistons nicely: drained, popped closed onto some wood (to restrict piston travel) with an air line and pulled back in (hand trigger operated wood clamp if stiff) to make sure they were both moving freely - not long since I cleaned them out anyway. The trick to getting the pistons back in under the bellows (last time when I took them out) was found to be some compressed air and some wood, the bellow literally blow themselves out over the pistons like a balloon. I hate dragging brakes. The trick is to use some wood and not lose any fingers
. Also when re-installing empty pistons the gravity from the reservoir bleeds them as there's no airlock, or at least it did on mine...
Fingers crossed the whine has gone and I just need to do the seal, will report back: I'm not brave enough to re-use the old steering knuckle nuts as I had to grind one off (They are fine pitch M10 x 1.25mm).
Average home mechanic in Cambridge, UK. Peugeot 406 1998 1.9 tdi GLX