<<Whats remote De-Icing? >>
At LHR, you deice "on stand". Causes problems in waiting for the deicing truck to appear and do the Biz. Then the clock starts running for "holdover time" (say 25 mins). You now have to be airborne in this time... You have to ensure everything goes well - from ground allowing you to push back, start up OK, no queue at Holding point etc., all a little unlikely given the conditions.
Alternative, say like Oslo, is start up, taxi out covered in snow etc, and stop near the runway holding point in a designated area. There you get deiced by designated teams that don't waste their time trundling around the airfield finding their "customers". When its done, you are right by the holding point, so off you go in 2-3 minutes. In addition, by the time you get to them, most of the other "hassles" associated with departure are solved...
However, it is a "system", and can't really be knocked up on the cuff in a day, especially somewhere like LHR which is chronically short of space. In addition, it really relies on 1 airfield run DeIcing company, which airline beancounters won't like because there is no competition over charges etc.
<<If conditions get so bad, how come LHR didnt just shut down>>
Conditions weren't necessarily "that bad" i.e. 'dangerous'. It just slowed everything down. It was hardly a safety hazard that the Virgin A340 ended up off the edge - who knows why - but I bet when it got pulled out it just needed a hose down. It really just added to the delays. Shutting the airfield down, as you suggest, would have caused 10x more inconvienience, and is a Hazard in itself leaving numerous airborne aircraft needing to divert into the limited capacity of other airfields ...
NoD