We are taught in school that words ending in S in English may or may not have an apostrophe.
But in London you can almost forget about it, because there is a lot of confusion in this matter and there is not much to do with logic.
I'll try to clarify a bit below, but I guess it's still be confusing.
Queen's Park
Everywhere with an apostrophe, but football team QPR disagrees.
Regent's Park
Yes
St James's Park
Yes
St John's Wood
Generally always, but the texts on the tube station platform are different.
St Paul's
Always
Shepherd's Bush
As a rule always, rare exceptions in the market.
Barons Court
Actually this area was never owned/ruled by barons.
Bounds Green
Although the name is derived from the surname Bounde, there is never an apostrophe in the name.
Bowes Park
Also by surname.
Canons Park
This was once the land of the canons. Monks have always been stingy, they save one character here as well. :-)
Colliers Wood
Named after the coal burners that once operated here. I really don't know whether to write Collier's or Colliers', either way.
Crews Hill
Devons Road
Gallions Reach
Gants Hill
Golders Green
Haydons Road
Highams Park
Palmers Green
Ponders End
Rayners Lane
Raynes Park
Whipps Cross
All by surname and traditionally without the apostrophe.
Parsons Green
There used to be an apostrophe, but it has been abandoned after the name of the tube station.
Earl's Court
Use an apostrophe in tube station and district names, but not in street and exhibition centre names.
King's Road
Is spelled differently in books, maps and street signs.
Queen's Road (Walthamstow)
Older street signs used an apostrophe, newer ones do not; however, it is always in the name of the station.
Queens Road (Peckham)
Street signs have different spellings.
St Johns
St Margarets (Richmond)
The
street and railway station do not have an apostrophe, but the church that gave the name does.
God's Own Junkyard
A quirky gallery in NE London. Google offers an apostrophe, but locally they think otherwise.