A day that began with a bomb scare ended with an explosion of joy from the Oxford supporters assembled at the finish line of the 163rd Boat Race. They saw their team justify their favouritism in a race they led from start to finish, albeit without their lead ever seeming insurmountable. Having won the toss of the ceremonial 1829 gold sovereign, their president, Michael Disanto, chose Surrey Station, which ought to have given Cambridge the advantage on the first bend. The light blues failed to make use of it, allowing their rivals to open a lead they would never relinquish. The official winning distance was one boat-length-and-a-quarter but it was closing as the crews inched towards Chiswick Bridge.

“It was hard work,” said James Cook, a veteran of two previous races and one of two brothers in the Oxford boat.

“We knew we were up against a very fast Cambridge crew, that there were some very fast rowers in that boat,” added his elder sibling Ollie, who managed to lose his winner’s medal in the depths as he and his team-mates gave cox Sam Collier the traditional soaking. “We knew on the race day that anything could happen. As brothers we don’t win too much but now I’ve won a medal and the Thames has already reclaimed it.”

On a day when the Cambridge women’s team crushed their rivals by 11 lengths in a record time of 18min 33sec after capitalising on a disastrous start in which Oxford’s Becca Esselstein almost lost her oar, racing had been threatened by the discovery of a second world war shell submerged in the murk near the start at Putney Bridge. The small piece of artillery was assessed and subsequently removed by police specialists whose colleagues – some heavily armed – maintained a visible presence as a reminder of other threats.

The Boat Race has its critics but it is what it is: a decent day out that is often derided as a symbol of the class elitism against which Trenton Oldfield claimed to be protesting when he disrupted the 2012 contest with a dip in the Thames. Despite his antics this sporting spectacle retains a curious appeal among millions with no particular interest in rowing or either university involved. Both banks and several bridges were thronged on a fine day for outdoor roistering, with up to 350,000 estimated to have convened at various vantage points in Putney, Hammersmith, Barnes and Chiswick. With millions more tuning in on TV, it is fair to say people are genuinely interested. Not all of them bray annoyingly, wear red trousers or sit on the Tory front bench.

One of the more intriguing subplots of this year’s race was the presence of William Warr in the Oxford bow seat against his former university. The 25‑year‑old became only the third man in the race’s history to switch sides and in the build-up made no secret of the fact that many of his former Cambridge friends barely speak to him any more. A loser in 2015 with Cambridge, when he was team-mates with the light blues Ben Ruble and Lance Tredell, Warr seemed curiously detached from his team’s raucous, champagne-soaked victory celebrations but denied his subdued demeanour was anything to do with his controversial switch.

“I was just really tired,” he said, having avoided the embarrassment of finishing a loser with both teams. “It was a hard-fought race because Cambridge were always there pushing us, so I was exhausted ... completely shattered. It was a great victory and a great race. Total respect to the opposition, from Cambridge too, because I know how hard it is to win this race.” Asked what he had said by way of commiseration to his vanquished former team‑mates, Warr revealed: “I just said ‘good race’, nothing much more than that.”

In his book The Last Amateurs: To Hell And Back With The Cambridge Boat Race Crew, Mark De Rond spent a year embedded with the oarsmen, risking all for a rare chance to race their Oxford rivals over four muddy miles of water and to be forever called a Blue‚ in 2007. “Why would these students swap dreaming spires for still dark mornings, for perpetual exhaustion, for rain and wind and damp clothes?” he asked.

“Why would anyone pursue anything where the personal investment is so very steep and yet the material reward non-existent? To train and remain forever an amateur.”

While the rowers of Cambridge could perhaps be forgiven for wondering why they bothered sacrificing time that could have been devoted to more traditionally hedonistic student pursuits for gruelling twice-daily training sessions and perishing early-morning starts throughout the winter months, the answers to De Rond’s questions were writ large on the pale, gaunt faces of the winners.

As they celebrated immediately after crossing the finish line, president Disanto seemed to capture the general mood as he rent the evening air with a loud and pre-watershed unfriendly “Fuck, yeah!”