Big School's second instalment scored 3.63m (17.4%) for BBC One on Friday (August 23), overnight data reveals.
The comedy, starring David Walliams and Catherine Tate, was down 610k on last week's debut, but was still the most watched programme of primetime outside the soaps and news.
Meanwhile, Celebrity Big Brother's second episode scored 2.05m (10.4%) for Channel 5 at 9pm, also down 610k on yesterday's opener. A further 104,000/0.7% caught the programme on +1, while Bit on the Side brought in 824k (6.5%) at 10.30pm (161k/2.3%).
On BBC One, The One Show interested 3.15m (17.8%) from 7pm, after which Nigel Slater's Dish of the Day appealed to 2.5m (12.6%) at 7.30pm. The latest episode of Celebrity MasterChef attracted 3.28m (15.5%) an hour later. Mrs Brown's Boys took 3.46m (17%) at 9.30pm.
BBC Two showed Great British Railway Journeys to 1.1m (5.7%) at 7.30pm. It was followed by Mastermind with 1.91m (9.6%) at 8pm and Gardeners' World on 1.87m (8.5%) at 8.30pm. The Burrowers: Animals Underground and The Trip then grabbed 1.86m (9%) and 660k (3.7%) respectively from 9pm.
On ITV, River Monsters was seen by 2.28m (11.5%) at 8pm (117k/0.6%), while Doc Martin scored 3.02m (14.7%) at 9pm (273k/1.7%).
Channel 4's Four Rooms secured 590k (2.9%) at 8pm (148k/0.7%), followed by Peter Kay Live at the Top of the Tower with 1.25m (6.3%) at 9pm (216k/1.4%). Peter Kay in Conversation had 1.01m (7%) at 10.15pm (209k/2.6%).
Back on Channel 5, coverage of The Ashes earned 711k (3.9%) at 7pm (43k/0.2%) and Paul Merton: World's Biggest Cruise Ship took 927k (4.5%) at 8pm (52k/0.3%).
Movie The Shawshank Redemption was the most watched broadcast on the multichannels, scoring 547k (3.2%) on ITV2 from 9pm.
