The second episode of the six-part crime drama, which despite the fall still won last night's 9pm slot, was watched by 4.8m viewers, according to unofficial overnight figures, well below last week' 6.2m viewers.
'The Fixer', which drew a 21.2% share of the audience, joins a growing band of ITV commissions such as 'The Palace', 'Moving Wallpaper' and 'Echo Beach', which have debuted this year with decent-sized audiences, only to tail off rapidly.
Five's 'Breaking into Tesco' is holding its audience since launching two weeks ago. The series, in which ambitious cooks compete for the chance to turn their recipes into products fit for the shelves of Tesco, pulled in 1.1m viewers and a 4.7% share at 9pm.
Channel 4's teatime ratings hit 'The Paul O'Grady Show' returned from a break with an impressive 2.5m viewers and a 17.4% share at 5pm-6pm. Including Channel 4+1 ratings, the show recorded 2.5m viewers and a 17.8% share.
The show dented the performance of Five's Australian soap 'Neighbours', which drew 2.1m viewers and a 12.4% share at 5.30pm.
Channel 4's Iraq programming around the fifth anniversary of the invasion was never going to earn big ratings, but the programmes performed well nonetheless considering the challenging content.
A documentary from Dispatches called 'Iraq - The Betrayal' with political journalist Peter Oborne netted 700,000 viewers and a 2.6% share at 8pm. Including Channel 4+1, the audience was the same and the share was 2.7%.
The documentary was followed by a film from acclaimed British documentary-maker Nick Broomfield called 'Battle for Haditha', which claimed 1m viewers and a 4.9% share at 9pm. Including Channel 4+1, the film managed 1.1m viewers and a 5% share.