Disco 4 (LR4) Advice on Disco roof rack whistle?

So my Disco 4 has what seems to be a common problem - whistling from the roof rack. It's definitely that, because when I take the rack off, the whistle goes away.

This happens at slow speed - 25mph - 40mph and is obviously more prevalent on open roads as opposed to more sheltered ones. It's the standard Land Rover locking rack.

Anyway, obviously I could just take them off...duh... but any advice on reducing the whistle? Have sent an email to FamousFour to see if they have anything suitable. I saw a topic on the web that said stretching a bungee cord around the front one in a mesh pattern can help... !? Also taping up channels and nuts and stuff, but it's so loud that I can't believe it's a specific area of the rack - must be the wind moving around near it?

Thanks.

Is the base covered in at all with chequer plate etc, I cured mine from whistling dixie by putting some plate on the base,, don't go straight out and buy some as there all different, i put some old carpet on first.

I got a brand new Brown church rack a few years ago which done the exact same.
I filled all the little holes in the tubing which took most of the whistle away!.

if you don't like the tune change channels