The first Challanger II's delivered to the British
Army went to the Royal Scots Dragoon Guard
of 7 Armored Brigade
(The Desert Rats) for service in Kosovo
The Challanger II, was brought without sand filters. In the snow and summer of Kosovo, this wasn't a problem. However, on excercise in Oman serious problems were discovered. The power packs had lifetimes of hours rather than days. Considering where The Desert Rats were named after, and where they had last fought in anger, this was a BIT of an oversight.
Challanger II was fitted with sand filters before the current war in Iraq. Thank god we went now and not two years ago.
Also one undocumented feature of the Challanger II is its boiling vessel. It's a fantastic device for the Infantry, as it stops them having to get out our hexi blocks and gas burners.
For other UK kit that doesn't work well in the desert look at
In fact, there isn't much Brit kit that works well anywhere. I guess thats up to the budget to sort out though.