St Helens moved two points clear at the top of the league thanks to a ruthless first half performance in London.
Both sides were missing several key players but it was St Helens who coped better, racking up a 0-34 half-time scoreline in an entertaining game.
Harlequins restored respectibillity to the procedings in the final 40 as they went over for four consolation tries.
Puletua completed his brace of tries with five minutes remaining and Leon Pryce snook over before the hooter to put Saints into a commanding lead at half-time.
It was a different Harlequins side who came out after the break however, and Haggerty went over for Londoners’ first try three minutes in.
Leon Pryce kicked his second 40/20 of the afternoon which gave Jon Wilkin the field position to burst over near to the line but that would prove to be Saints’ last score as Quin’s ended the game positively.
Danny Orr (43,50,70,78)
Kyle Eastmond (5,17,21,28,34,45)