A man has been arrested on suspicion of murder after the death of 21-year-old Finbar Sullivan, who was stabbed to death in London’s Primrose Hill.

The Metropolitan police arrested a 27-year-old man on Friday. A second man, who is 25, has also been arrested on suspicion of assisting an offender. Both remain in police custody.

Finbar Sullivan, 21, was stabbed in the north London park in the early evening on Tuesday and pronounced dead at the scene.

His father, Christopher Sullivan, had said his son had gone to the park to use a new camera he had been given for his birthday.

Another man, believed to be in his 20s, was also taken to hospital after being found nearby on Regent’s Park Road with stab wounds. His injuries were found to be non life-threatening.

DI Andy Griffin said: “My thoughts remain with Finbar’s family who continue to receive support from specialist officers at this unimaginably difficult time.”

Police said residents could expect to see an increased police presence in Primrose Hill and the surrounding areas.

Sullivan’s father, a musician and founder of the 1980s band Blue Rondo à la Turk, said his son had wanted to become a cameraman like his grandfather Michael Seresin, who worked on Harry Potter and the Prisoner of Azkaban and Rambo III.

“This is the worst tragedy I could ever imagine,” the 65-year-old said. “He’s my only son … I had him when I was 45. He can never be replaced. He’d just bought a new camera, we all chipped in for his 21st birthday, and he took it up there to do a bit of filming.”

After the arrests, police thanked members of the public who came forward with information, and encouraged others in Primrose Hill, a spot in the capital popular with tourists and residents, to do so, adding it “could have a huge impact on our investigation”.