John Spencer, the manager of the British & Irish Lions in New Zealand this summer, said he was “surprised and disappointed” at the critical remarks made by the Ireland flanker Sean O’Brien about Warren Gatland and one of the head coach’s assistants, Rob Howley, but ruled out initiating disciplinary action against the player, who started all three Tests.

The tourists drew a series they were widely expected to lose, becoming only the second Lions party not to lose a rubber in New Zealand, but in a radio interview O’Brien said he was critical of the management because he felt “we should have won it comfortably”. He claimed the players were overtrained on the Thursday before the first Test and said Owen Farrell and Johnny Sexton took over the attack coaching for the second Test because Howley was struggling to get his message across.

Spencer, who was a player on the winning 1971 tour in New Zealand, said: “This is the first time either during or since the tour that I have heard a player say anything like that. I was surprised and disappointed when I saw what Sean had said because it was a tour when everyone stuck together and showed great character to come back against a side that has been at the top of the world rankings for a very long time.

“I watched virtually all the training sessions and cannot see where Sean is coming from. He is a player who had a big impact on the series and I have considerable respect for him but while there was initial disappointment at the end of the third Test when the series was drawn and the dressing room was flat, people have come to realise what a considerable achievement it was, given all the unsuccessful tours there and the All Blacks’ pre-eminence this decade and further back.

“I thought the coaches [who included Ireland’s defence coach, Andy Farrell] did an incredibly good job and to me what Warren Gatland achieved in New Zealand on the back of the 2013 success in Australia makes him the best coach in the world. I have no criticism of any of the coaches and it was the best tour I have been on in terms of the relationship struck up between those involved. There was the right balance between hard work and fun.”

In 2001, the England scrum-halves Matt Dawson and Austin Healey were fined for critical comments about the management they made in newspaper columns during the Lions tour to Australia but Spencer is not considering disciplinary action. “I have no intention of taking the matter further,” he said. “Everyone is entitled to their opinion but when you consider what happened the last time the Lions were in New Zealand [losing 3-0 in 2005], you can definitely say that the Lions are now in a very good place.”

The Saracens No8 Billy Vunipola, who missed the tour because of injury, sided with O’Brien and maintained the Lions would have whitewashed New Zealand had Eddie Jones, the England head coach, been in charge. “I wasn’t there but I guess if he [O’Brien] is saying it and the authority he said it with, he’s probably right,” Vunipola said in a radio interview. “For me to sit here and say the Lions would have probably won is wrong. But personally my opinion is that if Eddie Jones went as coach they would have won 3-0. He is that good.”

Gatland and Howley did not respond to O’Brien’s remarks on Thursday but the Lions’ chief executive, John Feehan, defended them and the rest of the management team, saying: “I said all along that I think we had the best coaching team available and I think they proved that in what we achieved in New Zealand.

“To draw a series with the All Blacks, who had not lost a Test match at home for eight years, was a remarkable result and Warren and the coaches deserve huge credit. Against all the odds and with limited preparation time, this squad became only the second Lions team in history to either win or draw a series in New Zealand in 13 attempts.”