Mallinder junior has made a striking impression during the current campaign, having burst onto the scene back in January.
The 19-year-old centre scored the winning try on his Champions Cup debut, against Glasgow Warriors, and also registered in the following weekend’s win at Scarlets.
Those scores helped Saints progress to the quarter-finals and they will travel to Saracens for that last eight clash on Saturday.
Since January, Mallinder junior has been an increasingly important presence in the team, but his dad insists selection has not always been straightforward.
“Playing Harry was something was something I had to think twice about – more than twice,” the Saints boss said. “I think what you have to do is rely on your coaches a lot.
“I certainly looked to the advice of the three of the coaches (Dorian West, Alex King and Alan Dickens) to hopefully make sure that he’s always picked on merit.”
Owen Farrell and George Ford are examples of players who have flourished under the tuition of their fathers.
And Mallinder senior has been hugely impressed with the mature displays off his offspring.
“I think Harry’s become a key member of the squad,” he said. “You always want as many quality players as you can pushing to get into the team and your squad.
“Then it’s nice that you can rotate a little bit and play to those individual strengths, so you’re not committed to playing the same starting 15 every week. I think Harry has given us that option.
“We were looking for Tom Stephenson to play a large part this year, but unfortunately he injured his foot away at Racing.
“Then he made a comeback, played in a Wanderers game and had a recurrence, so that’s just about ruled him out for most of the season and suddenly you’re limited in terms of your centres.
“It’s nice that Harry has been able to come in and added to George Pisi and of course Luther (Burrell), who have been doing a lot of the workload up to now.”