The figures represent an approximate 2.8m drop year-on-year for the BBC One sitcom, which stars Robert Lindsay and Zoe Wanamaker.
The Old Guys amused only 3.33m (15.9%) for the show's second series launch, but still won its slot at 9.30pm. Earlier on the channel, an 8.30pm repeat of QI interested 2.66m (13.1%).
At 10.35pm, the penultimate Friday Night with Jonathan Ross had 2.98m (19.6%). It has recently been announced that the broadcaster will host a new chatshow on ITV next year.
Big Brother's live eviction attracted 2.46m (11.7%) and 2.38m (14.5%) to Channel 4 at 9pm and 10.30pm, while The IT Crowd entertained 1.71m (8.4%) at 10pm.
Dickinson's Real Deal and Doc Martin repeats put in 2.32m (11.9%) and 2.66m (12.7%) at 8pm and 9pm respectively.
Over on Five, Nature's Shock grabbed 483k (2.4%), then repeats of The Mentalist and CSI: NY were seen by 1.82m (8.7%) and 1.06m (5.5%).
BBC Two's coverage of this year's Hampton Court Palace Flower Show appealed to 1.8m (9%) in the 8pm hour, then coming-of-age drama Dive ended with 1.2m (5.7%) at 9pm.
Overall, BBC One beat ITV1 in primetime with 19.4% to 16.6%, followed by Channel 4, which averaged 8.1% (+1: 0.6%). BBC Two finished fourth with 6.7%, while Five had 4.6%.
Elsewhere, a repeat of Family Guy topped the multichannel ratings for the second week running, with 514k tuning in to BBC Three at 12.20am.
BARB ratings data supplied by Attentional