London accommodations

Single room? Double Room? Budget? "Decent" meaning what?

I go with what is familiar and has always been a good value for me. Premier Inns.

Be prepared, London is one of the higher priced hotel cities in Europe. Room size is generally small by American standards, unless you go very high end.

I also recommend Premier Inn. You can find one almost anywhere in London, comfortable beds, consistent quality, and reasonably priced.

I'll put a plug in for my favorite place....the Nadler Kensington.

I stayed there 99 nights in 2018.

Thanks for the advice. Sorry I didn't include more information in first post. Double room around $250 per night, non smoking.

If you can budget is $250/night I'd seriously consider an apartment. We've used London Connections https://londonconnection.com/
Very good service for an AirBNB type accommodation. I can't speak for what they have in Kensington, but they have many places scattered in the main hub of London.