Pauling's absence threw the American contingent to the gathering into some confusion. Corey and Caltech crystallographer Eddie Hughes, passports in order, were already in London. Pauling asked Hughes, a relative unknown who was far less comfortable in front of an audience than Pauling, to deliver his lecture. Armed with Pauling's manuscript and accompanying set of twenty slides, Hughes practiced the night before the meeting's opening session. It was a lengthy, detailed talk, but Hughes read it aloud until he managed to fit it within the expected hour-long slot.

The next morning, the British told him that he would have only twenty minutes. Corey spoke first while Hughes slashed at the manuscript. He was not done editing when his time came to speak, and managed to make it through only part of Pauling's detailed material before time ran out. The British gave him ten extra minutes. Hughes stumbled through to Pauling's conclusion – "In view of the success that has thus far been obtained by this method of attack, it seems justified to assume that proposed configurations of polypeptide chains that deviate largely from the structural principles that have now been formulated...may be ruled out of consideration." – before sitting down. Pauling would have delivered the line with ringing conviction. Hughes received scattered applause.

For the rest of the day, Hughes remembered, "The Englishmen sat there, telling us what was wrong." Astbury rose to voice his concerns about the mysterious 5.1 angstrom reflection, which Pauling's model did not explain, adding that Pauling's density calculations were not "reasonable," that Pauling had to his own peril ignored side-chain interactions, and that Pauling relied too much on data from synthetic polypeptide chains. Bernal stood up and noted the lack of proof for alpha helixes in globular proteins. Another researcher pointed to Pauling's overly free use of numerical corrections to answer critics. The criticism was withering. Only John Edsall, an American who spoke at the end of the day, lauded Pauling's alpha helix as "one of the great creative triumphs of thinking in the field of protein chemistry." Corey and Hughes were allowed just five minutes to answer their critics.

"I was very angry," Hughes stated. "I wrote Pauling and told him I thought we'd gotten a dirty deal."

"There was much discussion about your model of the alpha helix," Bragg wrote Pauling just after the meeting closed. "A number of people are still doubtful about it and you ought to have been there to answer their questions personally." Bragg added that he himself was convinced of the alpha helix's "essential correctness" – at least in synthetic polypeptides.