Former Swansea player Mackey was over the try line
twice in the first half and made the third try scored by Matthew Evans.
In the final seconds of the first period the visitors lost possession close to the try line
and Guy Manson- Bishop powered home.
Henley landed another penalty from in front of the posts and shortly afterwards scored a lucky try as the ball ricocheted off the centre's knee and landed over the try line
for the easiest of touchdowns.
Strong drives from Jonathon Byrom, Jacob Green and Joe Almond brought the home team within inches of the try line
, but Keighley held firm and added two more tries before Sam Pollard scored a converted try as half time approached.
He seemed to have lost control as a scrum five metres out, raced the Quins' try line
but the referee was on the spot to award the touchdown.
As a real thriller went into injury time with Northampton leading by a solitary point, Tatupu cut down Bath's England winger Adedayo Adebayo as the try line
With the score 6-6, a 44th-minute grubber kick from Fifita (left) forced an error from Jack Owens on his own try line
and the prop touched down for a converted try.
But they didn't have to wait long to cross the whitewash as their forwards proceeded to lay siege to the Quins try line
side pressing for the try line
but there was no way through the solid Blacks defence.
"When you get that close to the try line
you have to be focused.
After a series of powerful forward surges, Santiago Garcia Botta forced his way over the try line
, but the television match official ruled out the try with footage showing Cory Hill and Rob Evans having their hands underneath the ball.
Looking threatening with the ball in hand, they forced a repeat set by tackling Keighley over the try line
, but a knock on the next set offered the visitors the chance to relieve the pressure that had steadily built up.