Not another player, no...but other Heirs of the King could start there.
It may be a situation where the King does not WANT to start in London as no other non-Heir Blocks can usually start there with him, so the extra London card is not always worth taking for him...
I noticed you get a bonus card draw in the draw phase for controlling London and for controlling the king, but the only estate in London is a royal estate. So does the king essential get a 2 card bonus as long as he places himself in london, and only he can get this bonus for controlling london? Is there any way a player other than the king can control London in the draw phase?