IF FISHED FROM A FREE FISHING PUBLIC STAITHE / LOCATION ON A RIVER !!!!
You can take:
A total of 15 coarse fish (barbel, chub, common bream, common carp, crucian carp, dace, perch, pike, roach, rudd, silver bream, smelt or tench, including any hybrids of these species) of not more than 20cm per day (excluding grayling)
1 pike of not more than 65cm per day
2 grayling sized between 30cm and 38cm per day
You can also take any other coarse fish, including non-native species and ornamental varieties. You need permission from the owner to remove fish from still waters (this means any broad) and canal fisheries.
Eels or shad must be returned to the same water unharmed.
Fish that are not legal to keep must be returned immediately to the same water with as little injury as possible or retained in a keepnet or keepsack, and must be returned alive to the same water on or before completion of fishing.
The size of any fish is measured from the tip of the snout to the fork or cleft of the tail.
He is legally allowed to retain...although his method for unhooking is adding to the distress of the pike. Personally, if I wanted to retain for the pot (actually quite tasty if I remember, my dad cooked one about 30 years ago) dispatch quickly as per if you were sea fishing.
In this scenario, he would be unable to retain another pike, but could catch and retain a further 14 mixed course species as long as under 20cm in length...
For the record....I'm more conservation minded, I never retain, and fish purely for the sport, curiosity and to enjoy the surrounding environment. This more than satiates. But I would never discriminate against someone who is not breaching a byelaw, however much I question a particular part the byelaw.... Tight lines...take photos, not fish.