When I was in London in 2004 it was customary to drop off the key at the front desk, as in most of Europe. Is this still the case especially since I am not staying at what Americans would consider a traditional hotel?
It varies. Some hotels do this while others have upgraded to the keycard. It depends on the hotel.
You'll find out when you get to your hotel.
In general that is happening less often now due to the increased use of electronic key cards rather than traditional keys. If the guest loses or leaves town with a key card, the hotel quickly creates a new one. However, some hotels still use traditional keys, and occasionally they put a heavy piece of metal on the key ring so you are not inclined to walkout of the hotel with it. During the first six weeks of my current trip I've had one leave-at-the-desk key.
What don’t we yanks consider a “traditional hotel?”
Been traveling to London for decades. Haven’t done the room key drop off since the first Bush was in the White House.
Things change.