[Kojak]

There was a bit of a discussion a few years back at the blue place about an edition of the Nine that Peter Sissons hosted from Washington D.C., just as Bill Clinton was about to be impeached. In his book, he claimed that George Alagiah was the backup presenter in the studio - and this led to some discussion about whether Peter had misremembered, as there was no other record of him presenting in the virtual era. I can now confirm that you were all correct. The following video shows that it was in fact Edward Stourton presenting in London that evening:

youtu.be 

He said as well the only other instances her presented outside the studio were for Dunblane and the Concorde crash, so i'd guess George was the presenter for the Concorde broadcast.

That would make sense, as George seemed to be the designated fill-in for the Nine/Ten during the cream and red era. Even then, he only did about ten programmes a year - as we all know, it was very rare for both Peter and Michael Buerk to both be absent.