
The puppy will not need the amount of free running that a 3 or 11 year old adult dog will & I personally wouldnt run in a field at that age(garden excercise should be sufficient). My 6 month hasnt had free running, although it will be soon.
As a previous postee has said 5 mins per month, your pup should be getting 20 mins max.
It may not be their territory, as it is a field and I would control him anyway, he needs to learn respect for his elders & this means being put on a lead, so be it.