I've just changed my air con pipes and I spotted two vacuum hoses hanging. One I found out connects to a black plastic cylinder mounted on the inner wing but I can't see where the second one goes to

I don't know whether I've pulled it off accidentally when replacing the hose

Not off the Black plastic accumulator that sits to the top left against the suspension turret. I think it's to do with the vacuum for the turbo, sorrhy not in car so cant go and look.
No doubt someone will put me right. Mine was a blue one!

I think I've worked it out.

There were two pipes hanging. I spotted one port on the end of the reservoir. The other is on the vacuum valve that's mounted underneath the reservoir.
I'm hoping I've got them the right way round- I've connected the pipe from the turbo to the vacuum valve and the other pipe to the reservoir. Took it for a test drive and the turbo whistle I had last week has gone.
I must've disturbed it when I did the brake pipes. 2010 MY Vogue SE TDV8 3.6 Stornoway Grey- fully loaded

Sounds right. If you want me to check I can look at mine later unless someone has a picture handy. Mine was a blue one!

If you could, I'd be grateful. I phoned the dealer and he seems to think it's right. He did confirm that with a disconnected vacuum, it would overboost and over-fuel, causing the engine knock. 2010 MY Vogue SE TDV8 3.6 Stornoway Grey- fully loaded