Notice a squeak/ whistle/ whine from front of engine fan area on idle when cold on my 4.2 SC, not actively looked to see yet just wondered if anyone had similar? I'm thinking belt tensioner or even belt noise?

Yep, I got that too. When I first bought the car I thought it was just the belt slipping slightly due to alternator demand. But now the battery is well charged, and it still does it, I don't think it's that anymore.

From something I read (might even have been on here) I'm wondering if the cause could be the water pump. Not sure if it's the pump itself making the noise or whether it's being stiff to turn when cold and the extra drag is causing the belt to make that sort of squeaky-chirruping noise.

It doesn't seem to be causing any other problems, yet, but I'm resigned to having to deal with it at some point. You never know, we might get lucky, and a new belt might do the trick.

Guys, is this a known issue on the Jag-based engines or is it peculiar to the SC? 2006MY 4.2 SC
BMW R1250 GSA Rallye TE
Triumph Tiger 1050 (sold)
1979 Pontiac Trans Am (sold)

Yes it is a known issue there is a mod which changes one of the pulley brackets I think can't remember anyway the mod is a snip at about 250 quid - I just live with the squeak on cold

Could be the belts delaminating. Got mine changed and tensioner earlier this year. Make sure OEM belts used, as cheaper ones don't last long! Previous cars:
S-Max 2007-2013 (only diesel I've had, good car but expensive when diesely bits go wrong, so what's the point?)
Galaxy 2001-2007
Mondeo Estate 1997-2001
Sierra Estate 1993-1997
Uno Turbo 1987 -1993
Fiesta 1984 - 1987
Fiat 127 1982 - 1984

Very common issue.