Three of the other four race entrants had posted faster times than Viner of Highgate Harriers over the distance.
Viner commented: “The air temperature was 30 degrees so we started conservatively, and I made a real push over the final lap.”
The King’s College London student built up a seven-second lead over the final stages to finish in 17:05.96.
James Bongart, now 21, took bronze in the U23 javelin with a throw of 60.81m.
Joshua Firsht, 16, gained a full set of medals at the Independent Schools Association National Championships in Birmingham.
Firsht took gold in the U17 400m in 52.16, silver in the sprint relay and bronze in the 200m in 23.87.
“The hot conditions were perfect for racing”, Firsht said. “But the last 100m in the 400 was the hardest of my life.”
Younger brother Adam Firsht, 14, gained silver in the U15 800m in 2:08.25. Both athletes are pupils of Shoreham College, Sussex.
Highgate Harrier Idan Gal-Shohet, 17, placed second in the South of England U20 long jump championship at Crystal Palace, breaking the sand at 6.81m.
Richard Goodman, 24, cut his 5,000m personal best to 14:02.46 with a close second place finish in the British Milers Club in Watford.
David Stone, 15, reduced his 3,000m best to 9:00.54 in the Youth Development League in Reading.
Maccabiah-bound Ellie Edwards, 20, demonstrated exceptional form by setting a 100m PB of 12.28 at the Trafford AC Grand Prix at Stretford.
Younger sister Allana Edwards, 17, placed second in the U20 400m hurdles in 77.69.
Eden Davis, 18, has been selected to represent Great Britain at the Mannheim Open meet this weekend before departing for the Maccabiah.
Roger Bruck, now 78, made a successful return to the Alexander Stadium in Birmingham, 60 years after first competing there as a student.
Contesting the British Masters Championships, Bruck won gold in the long jump (3.32m) and high jump (1.20m), silver in the 200m (35.23) and bronze in the 100m (17.00).