Also works for up-hill. I was told to use it going up tracks as it detects any wheels starting to spin and puts that brake on - allowing all 4 wheels to work, rather than just spinning up one wheel. It does it much faster than you can manually and better than left foot braking.
I don't think this is correct at all.
If you select HDC and then so much as touch the accelerator, or the brake pedal then the HDC is over-ruled.
Try it on the level - select 1st gear and push the HDC button - you get a steady green light on the dash. If you then accelerate the HDC is inoperative (although the light is still steady green) so you go faster - take your foot off the accelerator and the HDC can be heard slowing you down, and you can then continue forwards at idle speed with the HDC operative. Much as willo describes in his post.
Try it again, but this time take your foot off the accelerator and gently touch the brake pedal - no HDC can be heard.
I think you may have confused the HDC when going uphill with the TC (Traction Control) which will brake the spinning wheel exactly as you describe. The TC light will flash momentarily as it cuts in.
This is also as I understand it from the Owner's Handbook.
AFAIK you can not switch off the TC (Hard luck - Jeremy Clarkson types)
I've only had wheel-spin on a Freelander in 2 situations -
First was all wheels on sheet ice.
The other is when I tried to defeat the laws of gravity by climbing a hill in a muddy field - all 4 wheels were turning slowly and forwrd motion ceased!!
That would be a situation for having A/T tyres - or I should have brought the Unimog.
Singvogel.