There were debuts for Tipperary’s Lee Mackey and former Westmeath captain Brian Smyth against the Westerners, although the latter could face a spell on the sidelines after suffering a shoulder injury.
Mackey, however, impressed, as did captain Colm Quinn, while Martin Finn fired 1-6 in his first game of the year following knee surgery.
Finn’s 16th-minute goal put London in control after a roaring start, but indiscipline allowed Kenny Feeney to drag Mayo back into contention, his trio of late frees cutting their deficit to three points (1-6 to 0-6) at the break.
A fortuitous Quinn goal eight minutes after the restart put the game beyond Mayo, before Henry Vaughan cracked home a third after Mayo goalkeeper Donal O’Brien had blasted a penalty over the bar. Feeney grabbed a consolation goal late on, but London finished strongly with a flurry of points.
Scorers for London: M Finn 1-6 (4f), C Quinn 1-3, H Vaughan 1-2, P Sloane 0-4, K Bolger 0-2, E Cooney 0-1.
Scorers for Mayo: K Feeney 1-8 (8f), C Freeman, D O’Brien (pen) 0-1 each.
LONDON: T Williams; E Walsh, B Costello, G Fennelly; M Walsh, PJ Rowe, L Mackey; C Quinn, K Bolger; P Sloane, B Smyth, H Vaughan; T Dunne, M Finn, L Hand.
Subs: S Ryan for Smyth (ht), K Walsh for Dunne (50), D Maher for Hand (52), M Ryan for Walsh (59), E Cooney for Finn (63).
MAYO: D O’Brien; A Brennan, A Connolly, S Connell; S Morley, D McConn, G Henry; P O’Grady, C Freeman; C McCrudden, D McDonnell, K Feeney; B Hunt, B Cullinane, S Hoban.
Subs: C Charlton for O’Grady (39), S Markham for Hunt (60), F Lyons for Henry (65), G Nolan for Cullinane (68).
Referee: P Murphy (Carlow).