Mallinder: Harrison a must for England
The 23-year-old grew up in New Zealand, but is England qualified through his Derby-born father.
He joined Northampton's academy in 2011, after catching the eye of England Grand Slam-winning captain Dylan Hartley - when the Saints star, who also grew up in New Zealand, was on a visit to his homeland.
Mallinder, asked after Saturday's match if Harrison should be picked for the second-string England Saxons, instead urged England coach Eddie Jones to consider the versatile loose forward for the senior side's trip to Australia.
"Teimana was outstanding," said Mallinder.
"He's been good for us all year. I'd say he should be on the tour to Australia - I definitely think that.
"He's not particularly big for a No.8, but he plays above his weight. Some of his carrying was absolutely immense.
"Teimana and Ben Nutley swarming everywhere looking for turnovers was a massive positive against Saracens.
"He's been improving for us over the last few years and I think we've seen a level of consistent performance from his this year to suggest he can go on and play at a higher level.
"I think he's probably best for England at No.7. He plays well for us at No.8, but I think probably at international level he's a No.7."
Agence France-Presse