I've had a quick read of threads, but not too clear what this definitely is.. The power steering has completely failed and whilst the engine is running, there's a hissing benind the off side front wheel. Any thoughts?

Owned the car for a week - great!

Sounds like your auxiliary belt has slipped or broken... Probably a tensioner pulley that broke causing the belt to rub causing the hissing sound....

You'll probably find you A/C won’t work either

I'd get it into a garage if I were you! Freelander 2 TD4 Auto, SE, Narvik Black, Alpaca full leather, Rear Headrest Entertainment System, 6 CD, 18 HSE Wheels, Privicy tints

Thanks. It's been towed. The hissing sounded like a leak, but could well be what you mentioned.