William Woods shot London’s lights out in Ruislip as Louth booked their place in Monday’s qualifiers draw.
The St Finbar’s clubman kicked 13 points, 12 coming from placed balls as the Wee County attack ran the home side ragged.
It is Louth’s first victory since beating Kildare in the O’Byrne Cup on January 3 and while issues remain in defence, Pete McGrath will be delighted with the accuracy of his forward line, who registered just three wides.
Louth needed a good start after their disappointing loss to Carlow last month and they got it with three points inside the opening two minutes, but the teams were back level by the 10-minute mark when Ryan Elliott capped off a flowing London move by rounding goalkeeper Neil Gallagher and finishing to the net.
The black-carding of Louth native Martin Carroll stalled the Exiles’ momentum, though, and they found themselves five points down on 18 minutes when Ronan Holcroft cut inside and buried a superb shot past Gavin McEvoy.
The scores continued to flow, with London managing to stay in touch courtesy of placed balls, but they were dealt a hammer blow two minutes before the break when they gave away possession cheaply on halfway and full-forward Conor Grimes fisted a high ball to the net.
That gave Louth a 2-12 to 1-9 half-time lead and they made the game safe early in the second period with five unanswered points, three coming from the dependable Woods.
Similar to the first half, London hit a purple patch and managed to reduce their deficit to four points, but they then went scoreless for 10 minutes as Louth pulled clear once again.
Woods’ only negative of a fine afternoon was blazing a penalty over the bar, but it mattered little as he tagged on another four points in the closing stages for an impressive personal haul.
Scorers: Louth: W Woods 0-13 (11f, 0-1pen), R Holcroft, C Grimes 1-1 each, D Byrne, C Downey, G McSorley 0-3 each, A McDonnell, T Durnin 0-1 each.
London: A Moyles 0-10 (6f), R Elliott 1-1, F McMahon 0-3, L Gavaghan 0-2 (2f), M Gottsche (f), K Butler, L Irwin 0-1 each.
Louth: N Gallagher; D Marks, E Carolan, J Craven; D Maguire, B Duffy, A Williams; A McDonnell, T Durnin; C Downey, D Byrne, G McSorley; W Woods, C Grimes, R Holcroft.
Subs: N Conlon for Holcroft (54, black card), T McEnaney for Downey (60), F Donohoe for Marks (65), E Lafferty for Williams (66), A O’Brien for McSorley (70).
London: G McEvoy; P Butler, C Dunne, C Murphy; D Carrabine, R Jones, P Begley; A McDermott, M Carroll; A Moyles, M Gottsche, T Waters; R Elliott, L Gavaghan, F McMahon.
Subs: G Byrne for Carroll (16, black card), M Walsh for Jones (ht), C O’Neill for Butler (37), L Irwin for McDermott (46), E Murray for Carrabine (49, bc), K Butler for Murphy (50),
Referee: P Hughes (Armagh).