After competing tenaciously with their Premiership opponents for the first 50 minutes of an entertaining pre-season encounter, the Reds succumbed to defeat in the final stages.
While few would have claimed Quins were the deserved winners, the 19-point margin was a harsh verdict on the efforts of the home side. On a warm summer's evening there was an excellent atmosphere at Stade Santander International, with more than 2,000 spectators in attendance.
Jersey were under pressure right from the kick-off, defending on their own line within 60 seconds, but held firm and worked their way back into the game and forced Quins' to show their defensive mettle.
The first score came from an attack by the visitors, but possession was lost and a lightning counter-attack saw Brett Herron pounce on the loose ball and find Will Homer, who quickly fed Jason Worrall for a 60-metre dash to the line.
Hooker Max Crumpton scored the equalising try for Quins from close-range and the Londoners then snatched the lead from the last play of the half, seizing possession from a loose Jersey lineout, forcing a penalty and then working the ball right for Aaron Morris to cross after swift hands from his colleagues in the back-line, including a scoring pass from Scotland international Tim Visser.
Herron's cross-kick set up the Reds' second try, finished by Auguy Slowik, but that sparked the visitors into action, with the forwards stepping up the pace and claiming two quick-fire tries through Dave Ward and Luke Wallace. By this point the home side were down to 14 men after back row man Kyle Hatherell was shown a yellow card.
The hosts were pressing for a third try to get back into the game but in doing so telegraphed their intentions and enabled Charlie Walker to intercept inside his own 22 and race 80 metres to the posts at the other end.
Jersey Reds
Tries: Worrall 17, Slowik 50
Conversions: Herron 17, 50
Harlequins
Tries: Crumpton 25, Morris 40, Ward 54, Wallace 62, Walker 70
Conversions: Swiel 25, 40, 54, 70
Referee: Karl Dickson. Assistants: Clare Daniels, Ian Bibey
Attendance: 2,052
Half-time: 7-14
Man-of-the-match as chosen by match sponsor Santander International: Aaron Morris (Harlequins)
Jersey Reds
Slowik; Worrall, Newey, Ma'afu (c), Stapley; Herron, Homer; Holsenstein, Maddison, Atalifo, Beckett, Batt, Bartle, Geldenhuys, Hatherell (YC 60).
Replacements: Selway, Morley, Rodman, McKern, Sexton, Joyce; Mudariki, Marx, Eastwell, Van Dam
Harlequins
Morris; Walker, Cheeseman, Tapuai, Visser; Swiel, Mulchrone (c); Boyce, Crumpton, Collier, Merrick, Glynn, South, Wallace, White.
Replacements: Ward, Lambert, Swainston, Kenningham, Tizard, Lewis, Murley, Waters, Barlow