Champions Antrim won through to the 2007 Ulster SHC decider but they were made to sweat for this semi-final victory at Casement Park.
Adrian Pierce, Barry Solan and Anthony Kane lashed home goals for London but the Saffrons were just too strong, having led 4-12 to 1-01 at the break.
Antrim led 2-01 to 0-00 after four minutes with Johnny McIntosh, from a 21-yard free, and Kieran Kelly, from open play, registering early goals.
Kelly and Michael Herron raised two more green flags before Martin Finn ended London’s wait for their opening score by pointing a 33rd-minute free.
Antrim overcame the first hurdle on the way to a sixth successive Ulster title but joint managers Dominic McKinley and Terence McNaughton will not have been pleased with the way their side relaxed after a prolific first half performance.
The Saffrons, who included championship debutants Ryan McGarry, Neal McAuley and Paul Shiels, looked in a mean mood as they cantered towards a 20-point half-time lead.
With the Exiles suffering from a number of withdrawals, wind-backed Antrim cruelly exposed the gaps in the visitors’ defence with two goals inside the opening four minutes.
McIntosh, who was unfortunately forced off with a knee injury, rammed home a close range free to chalk up Antrim’s first goal after barely 70 seconds.
Kelly followed suit just three minutes later and points from Brian Delargy, Brendan Herron and Karl McKeegan raced the home side clear.
Some clever stick work from the Antrim forwards played in Michael Herron for a 22nd-minute major and full-forward Kelly netted his second by lobbing the sliotar over the stranded London goalkeeper JJ Burke.
Delargy and Shiels added further points before London belatedly opened their account through Finn’s placed ball. Sloppy defending allowed Finn to find Pierce for his goal just before the break – the London wing-back made no mistake with a low, drilled shot from 14 yards out.
With a bit more respectability on the scoreboard, London, now with the wind at their backs, took on their task with renewed relish in the second half and managed to add 2-3 to their tally before Antrim set the umpires to work again.
Finn bisected the posts with a brace of frees before Solan slipped through to notch London’s second goal. Their third green flag came with a bit of good fortune as midfielder Kane dangled a long ball into the Saffrons’ square and a mix-up between ‘keeper McGarry and Michael McCambridge saw the net bulge.
Antrim steadied themselves somewhat with four unanswered points – Karl Stewart and substitutes Brian McFall and Simon McCrory were all on target – but they still leaked late scores to the impressive Finn, who top-scored with 0-6 for London, and substitute Ian Rocks to leave McKinley and McNaughton with plenty of food for thought ahead of the Ulster final on May 27.
ANTRIM: R McGarry; M Kettle, M McCambridge, Sean Delargy; N McAuley, J Campbell, C Herron; B Herron (0-3), K McKeegan (0-02, 1f, 1 '65'); K Stewart (0-02), B Delargy (0-03), M Herron (1-01); J McIntosh (1-00), K Kelly (2-01), P Shiels (0-01)
Subs used: Brian McFall (0-02) for McIntosh, C Duffin for B Delargy, J McKeague for McCambridge, S McCrory (0-01) for Shiels, E McCloskey for Stewart.
LONDON: JJ Burke; E Leamy, S McLoughlin, B Forde; A Pierce (1-00), F McMahon, K Kennedy; B Solan (1-00), A Kane (1-01); K McMullen, B Tennyson, D Skehan; P Fagan, M Finn (0-06, 4f), S Malone.
Subs used: I Rocks (0-01) for Tennyson, E Kirkland for Malone, B Earley for Solan, C Buckley for Burke.
Referee: Tiernach Mahon (Fermanagh).