Hastily scheduled after yesterday's announcement from the couple, William and Kate - The Royal Engagement was watched by a combined audience of 5.92m (26.2%) on ITV1 from 7pm.
A special BBC documentary on the Royal Engagement attracted 2.57m (10.6%) to BBC Two between 7.30pm and 8pm. An edition of The One Show featuring coverage of Prince William's big news appealed to 6.48m (29%) on BBC One from 7pm, up a massive 1.5m week-on-week.
The second part of mini-series The Zoo averaged 4.12m (17%) for ITV1 in the 8pm hour, up 720k week-on-week. However, it was outperformed by Holby City, which entertained a healthy 5.86m (24.3%) on BBC One.
I'm a Celebrity... Get Me Out of Here! grabbed 8.61m (34.1%) on ITV1 from 9pm, beating BBC One's Turn Back Time: The High Street, which had 4.62m (18.1%).
The return of Channel 4's The Family was lost against such strong competition, pulling in just 1.03m in the 9pm hour and 211k (1.2%) on timeshift.
Also on Channel 4, Celebrity Coach Trip entertained a steady 2.18m (13%) from 5.30pm and 215k (1%) an hour later. Later, Kirsty's Homemade Home fetched 2.09m (8.7%) in the 8pm hour and 151k (0.6%) on +1. Jimmy Carr Telling Jokes amused 1.03m (5.8%) from 10pm and 171k (1.9%) on timeshift.
BBC Two's Coast pulled in 1.49m (6.6%) from 7pm. Alan Titchmarsh's Garden Secrets captivated 1.76m (7.3%) in the 8pm hour, before Horizon educated 1.19m (4.7%). Later Live with Jools Holland then appealed to 720k (3.5%) from 10pm.
On Channel 5, Street Market Chefs entertained 335k (1.4%) from 7.30pm. It was followed by Sea Patrol UK, which thrilled 957k (4%). CSI: Miami and CSI: NY grabbed respective audiences of 1.75m (6.8%) and 1.17m (6.2%) from 9pm.
Overall, ITV1 won primetime with 23.7% against BBC One's 22.8%. BBC Two came in third with 6.2%, followed by Channel 4 with 5.3% (+1: 0.6%) and Channel 5 with 4.5%.
Elsewhere, I'm a Celebrity... Get Me Out of Here now! brought in 708k (4.3%) on ITV2 from 10pm and 96k (1.2%) on timeshift. The programme was preceded by a new episode of The Vampire Diaries, which grabbed 383k (1.5%) and 204k (1.1%) an hour later.
Lesbian drama Lip Service continued to 534k (4%) on BBC Three between 10.30pm and 11.30pm.
BARB ratings data supplied by Attentional