I passed through St. Pancras daily for three and a half years, travelling to work.
The rings have, sadly, gone but Sir John Betjemen remains. The statue is there as a tribute to the man who saved St Pancras from the Bulldozer in the 1960’s.
It’s a wonderful station, that has been (in my opinion) delightfully restored. Most commuters will try and pass through as quickly as possible without regard for the majestic surroundings. When I had time I used to enjoy walking through the station and taking in the sights and sounds. Sadly, most days it was a quick rush from the Victoria Line up to the High Speed Javelins.
You’ll find the Olympic rings, well a quarter of each ring, by platforms 11,12 and 13 at St. Pancras, the home of the Javelins. The rings were cut up after the games and you can find more at Ebbsfleet, Stratford Intl and Ashford Intl.