Susan Boyle's appearance managed 6.35m (27.9%) on ITV1 and an HD audience of 243k (1.1%) from 9.30pm, making the episode the second most-watched ever, ahead of Simon Cowell's interview but behind Cheryl Cole's face-to-face.
Prior to Life Stories, American Anthems Week on The X Factor delivered a total of 12.33m (47.7%) from 7.45pm, peaking at 13.07m (50%) between 8.45pm and 9pm for Wagner's crazy rendition of 'Viva Las Vegas'. The Xtra Factor claimed 829k (3.8%) immediately after the main show on ITV2.
Strictly Come Dancing held a reasonably steady 10.26m (44%) for BBC One from 6.15pm, reaching a high of 11.44m (47.4%) between 7.15pm and 7.30pm, while All Star Family Fortunes, You've Been Framed and Harry Hill's TV Burp mustered 3.54m (16.4%), 3.99m (17%) and 4.96m (20.7%) on the other side.
Elsewhere on BBC One, Merlin attracted 5.6m (22.1%) for 'Love In The Time Of Dragons' after Strictly, Casualty logged 4.03m (15.6%) at 8.45pm, and Armstrong & Miller amused 2.94m (12.5%).
Channel 4 picked up 850k (3.3%) and 1.24m (5.1%) for Apocalypse: The Second World War and The Pillars Of The Earth, before 1.5m (8%) caught The Million Pound Drop from 10pm.
Meanwhile, Channel 5 grabbed 1.16m (5%) and 923k (5.5%) for a double bill of CSI from 9pm. Earlier, The Mentalist and NCIS notched up 551k (2.2%) and 964k (3.7%).
BBC Two's 8pm repeat of Dad's Army entertained 1.76m (6.8%), then 1.28m (4.9%) tuned in for Timewatch: The Last Day Of World War I. Have I Got A Bit More News For You fetched the channel's best audience of the day, with 2.09m (9%) at 9.30pm.
Overall, ITV1 beat BBC One in primetime with a share of 35.1% to 22.3%, BBC Two was third with 6.1%, Channel 4 followed with 4.3% (+1: 0.4%), and Five was last with 3.8%.
BARB ratings data supplied by Attentional