I thought I had a wheel bearing on its way out, rumble / whine that increases with road speed and doesn't change when the clutch is dipped. So today I jacked up each wheel span them and checked the at 12 and 6 the at 3 and 9. All good. Could it be tires? They have only done 8k and have loads of meat left. Or could it be something else?

Switch 2 wheels round and see if the noise moves.

I thought I had wheel bearing noise, in the end it was tyres worn unevenly. Swapped onto winter tyres and problem solved.

Same here, swap the wheels around and see if the noise moves with them.  Also in my case there was more noise and vibration when it was on the front and when cornering so you could try that. 

I guarantee that your tyres will have worn unevenly in a sawtooth pattern this causes terrible road noise.  I have had this issue on my current focus and my old focus.  Its actually worse on my current focus.  Think its a characteristic of the car to be honest.

Thanks for the replies guys, I do seem to remember years ago changing the wheels around on a car, but it wasn't until it came up here I remembered. I've got round the problem now. I've part X'ed it and brought a 9 mth old Focus.

I had a wheel bearing issue many years ago on my Renault 18. The noise is unmistakable, it's a hum which gets louder with speed. From that experience, I'll always know if I have a wheel bearing issue.