I'm so glad this is your family.
I looked a little further yesterday into the NL Gardiners and,as I mentioned before, there was a Hubert S. Gardiner in Flowers Cove who was born in Bareneed. I checked in Flowers Cove and found a Mildred Gardiner Crocker d/o H. Stanley from Flowers Cove who is quoted in a book "This is our Place, This is our Home" about life in northern NL. She says her dad was born in Port-de-Grave (which is also close to Bareneed) and his ancestors had come to NL from England.
She says Stanley's mother died when he was 9 mths old and he was raised by his Uncle Hayward Whalen in Flower's Cove. Turns out Stanley's dad is Robert W. Gardiner b 1886 (WWI Veteran)who d 1946 s/o Wm J. & Mary Anne of Bareneed. I would be willing to bet that Robert is a cousin of your John
b 1885. Robert is listed in the St. John's Phone Directory in 1938 & 1946 as R.W. Gardener, Signal Hill Rd., Lighthouse Keeper. Poor Robert didn't have much luck with the wives though - his 2nd wife Mary Catherine died in the torpedoing of the SS Caribou in 1942 (ferry crossing from North Sydney to Port aux Basques). His daughter Florence who was raised by Wm J. & Mary married Louis Newell and moved to Verdun, PQ. He had three children with Mary Kate - Eric (WWII Veteran). He may have married Hilda May Hall and died in Ottawa. Doug married Betty and may have lived in San Jose, California. Phyllis Louise married ? Fleuriau (he's not mentioned in her obit so they may have divorced) d 2007 St. John's. Phyllis had two daughters - Sandra & Denise.
Stanley, Flowers Cove, (he was a game warden & fisheries officer) had one other child besides Mildred who lived (3 died young) and that was Jock. Mildred ran a bed and breakfast apparently in Trout River, NL and had at least one son Blaine who is mentioned in the book. Jock had at least two sons. I found a telephone # for one of the sons if you'd like to contact me directly. He may be able to put you in contact with someone who could help in your search.
My email is firstname.lastname@example.org
Have a great day,