c4countdown

Assuming Countdown is not a general knowledge quiz show technically (i.e. sets puzzles rather than asks questions on facts) and also discounting the interactive TV quiz game Bamboozle (over 6,000 shows) and radio quizzes like PopMaster - no, that’s not because they’ve all got 9 letters in their names!

Fifteen-to-One ran from 1988-2003 and from 2014-2019 and aired

2,687 episodes overall, including:
2,265 regular episodes (1988-2003)
370 revived episodes (2014-2019)
40 schools episodes (1999)
10 celebrity specials (1990, 1992, 2013-2015) Adam Hills did the other 8
1 Champion of Champions episode (1997)
1 Milliennium Quiz episode (1999)

However, The Chase is getting very close.

As I write this, it’s currently on repeats and new episodes will air in January 2026 presumably, but as of 29th November 2025;

The Chase has ran since 2009 and has aired

2,512 episodes overall, including:
2,335 regular episodes (NB: 4 of these include 2 Text Santa and 2 Soccer Aid specials at regular 5 pm slot)
155 celebrity episodes
22 family episodes

Bradley Walsh (2,512) has already overtaken William G. Stewart (2,309).

What about total number of contestants?

Over 34,000 on 15-1 vs over 10,000 for The Chase.

Honourable mention: children’s favourite 50/50 had 11,800 contestants. The 1% Club needs to get to 119 episodes to surpass that.

Back in the 80s there was a game show called Ultra Quiz - each episode had 1000 players. The concept was basically multiple choice questions and the players had to go and stand in the area where they thought the right answer was, and were eliminated once they were wrong.

https://youtu.be/3fmM7VPj2Ms?t=834 (my mum was on this episode!)

Edit - seems it was each series started with 1000 and whittled down, so possbily not as many as I thought!