Ive just changed the oil and filters on the FFRR and I noticed an inline filter attached to a pipe, fixed just behind the fuel filter. The strange thing is, there's nothing connected to the other side of it.
It appears to be coming from underneath the cam cover, so I'm assuming it's a breather of some description. However, I've found a further two stray pipes just hanging around nearby, which has got me wondering if there's something missing that connects all three? 2010 MY Vogue SE TDV8 3.6 Stornoway Grey- fully loaded

It's a breather for the gearbox

Is it not the crankcase breather? My Previous RR's!
2018 P400e Autobiography
2008 TDV8 Vogue
2006 TD6 Vogue
2007 TDV8 Vogue
2007 RRS (I know, it doesn't count!)
2005 4.4 Vogue on LPG
2005 TD6 Vogue
2003 4.4 Vogue
2001 4.6 HSE
2000 2.5 DHSE
1999 4.6 HSE
1997 4.6 HSE on LPG
1995 2.5 DSE
1989 3.9 EFI classic
1988 3.5 EFI classic

No, it's for the gearbox and only connected at one end

as long as thats how it should be, I'm not bothered!

(must get a Haynes type manual!) 2010 MY Vogue SE TDV8 3.6 Stornoway Grey- fully loaded

No, you need the RAVE. See the wiki. 
RRC 2Dr, RRC 4Dr,
P38, and 2 L322s
(wife thinks I'm nuts - prob right, too)