The BBC One legal drama, which was last night recommissioned for a third run, dipped to 4.21m (18.5%) for its series two climax in the 9pm hour.
Starring Rupert Penry-Jones and Maxine Peake, the show's finale was moved to Wednesday so that it did not face ITV's England Euro 2012 football match on Tuesday, June 19.
The series has averaged 4.88m (20.9%) over all six episodes, only marginally down on the 4.95m (20.2%) for last year's premiere run.
Elsewhere on BBC One, the finale double-bill of True Love enthralled just 1.77m (13.1%) from 10.35pm and 1.49m (15.1%) at 11.05pm. EastEnders was predictably the channel's most-watched broadcast.
A Midsomer Murders repeat mustered 3.24m (14.5%) for ITV1 between 8pm and 10pm, adding 246k (1.2%) on +1. Emmerdale and Corrie won their slots in the 7pm hour.
Over on BBC Two, Ocean Giants (1.73m/7.9%) and The Secret History of Our Streets (1.96m/8.6%) were screened to decent audiences.
For Channel 5, NCIS logged 1.39m (6.1%) at 9pm and 208k (1.1%) on timeshift, while Big Brother entertained 1.33m (7.4%).
Overall, BBC One topped primetime with 22.7%, ahead of ITV1's 18.3% (+1: 1%). BBC Two claimed third place with 6.9%, followed by Channel 4's 6% (+1: 1.4%), and Channel 5's 4.8% (+1: 0.3%).
James Bond movie Quantum of Solace was the best-rated multichannel show of the evening with 1.03m (5.3%) for ITV2 between 9pm and 11.15pm and 284k (2.2%) on +1.
BARB ratings data supplied by Attentional