On my and dare I say every other 2.7 I have a round 3 inch ish valve like thing at top right of engine with a small inlet/outlet sticking out. No hose.
Anyone know what it is please ?
Also, mine is now starting without pressing the brake pedal first, is that normal ?

Don't know about the "valve" but my old 2007 2.7TDV6 i never had to press the brake to start it, think that only came in with the facelift in 2009 2015 L494 SDV6 3.0 HSE Loire Blue
2006 L320 4.2 Supercharged - Gone
2009 BMW X5 M-Sport - Gone
2007 L320 2.7TDV6 SE Buckingham Blue - Gone
2011 Jaguar XFS 3.0V6 Diesel - Gone
2009 (59) L320 Facelift 3.0TDV6 HSE White Wrap - Gone
2008 BMW X5 M-Sport - Gone
2005 Audi A6 3.2V6 Quattro S-Line - Gone

Ah right. Mine is 2008.
The round valve thing is under the engine cover.