New Countdown conundrum after ratings slump: Is the clock ticking on show's future? At its peak it was watched by up to four million but on Tuesday it managed just 260,000 viewers – the lowest in its history Afternoon slump: Nick Hewer with Susie Dent and Rachel Riley Channel 4 Bosses on Countdown are grappling with a new conundrum – GNIHSNIFI.It spells “finishing” – and that’s what may be on the cards for the letter and numbers show if viewing figures continue to fall.At its peak under Richard Whiteley the Channel 4 favourite was watched by up to four million.But Tuesday’s edition managed just 260,000 viewers – the lowest in its history.On other days this week the 30-year-old series, hosted by Nick Hewer and Rachel Riley, struggled to reach 400,000.A TV source said: “Countdown is cheap to make but these figures are very worrying."The clock is ticking and this signals the beginning of the end.“How much longer will they stick with something that has lost so man