I have the front of the car up on axle stands to replace the ARB bushes and drop links as I have a rattle going over bumps at low speed from the left front. This seems to be a possible cause so though as its not expensive I 'd try this.

While I have the car up I was looking at other bits of the suspension and I'm wondering what is the normal amount of play in the banana arm?
If I pull it up with my hand, using the ARB as an anchor I can move it quite a lot. The bush at the sub-frame end seems quite pliable.
Should the arm move when you tug at it with your hand?

 

 

I would say you'd see slight movement applying pressure with a 2 or 3 foot breaker bar but no slop.

 

You should not be able to move the arm easily like that. Once it starts to go, the wheels will track-out and start to wear out the inside edge of the tyre treads. When mine were going on my last X350, the tyres wear wearing, but the mechanic had to use a bar to show the wear. I was told they had had cars in where the arms had been hitting the subframe the bushes were so knackered ! Owner neglect, of course.