Channel 4's The Secret Millionaire show went from strength-to-strength last night as it claimed the top spot at 9pm with 4.2m viewers (18.7%), a new personal best for the show.

The hour-long show managed to build its audience up to a peak of 4.6m (20%) in the final quarter of an hour

Last night's show was up by 82.6% on the channel's performance for the year so far of 2.3m (9.7%). In 2007, C4 averaged 2.7m (11.6%) in that particular slot.

The show then attracted a further 317,000 when it aired on C4+1 an hour later.

Not too far behind C4 at the time was BBC1's one-off factual show Pedigree Dogs Exposed which held a steady audience of 3.9m (17.5%) in the same slot.

Five managed to squeeze out ITV1 for third place as the ongoing sixth series of CSI: Miami grabbed 2.7m (11.8%), also at 9pm.

ITV1's style show Trinny and Susannah Undress the Nation continued its downward spiral with a new series low of 2.1m (9.5%). The commercial network has averaged 4.5m (19.5%) in that slot so far this year.

Adding on an extra 100,000 from the previous week was the second outing of BBC2's Maestro with 1.8m (7.9%).

BBC2 was in a much stronger position at 8pm as the finale of Jimmy Doherty's Farming Heroes hit 2.6m (12%) over an hour, easily putting its nearest rivals in the shade.

C4's Don't Blame the Builder at 8pm had a modest 1.5m 97%) while Five's Julius Caesar and the Druids managed 1.1m (4.9%).

BBC1's EastEnders at 8pm had no problems with 7.5m (34.5%) which was followed by a My Family at 8.30pm on 4.7m (21.5%).

All hours shares for Tuesday 19 August 2008: BBC1 - 30.3%, ITV1 - 14.5%, C4 - 7.6% (C4+1 - 0.7%), BBC2 - 7.1%, Five - 5.6%, multichannel - 34.2%.

Peaktime (6pm to 10.30pm) shares: BBC1 - 26%, ITV1 - 18.3%, C4 - 11% (C4+1 - 0.6%), BBC2 - 7.8%, Five - 6.3%, multichannel - 30%.