Willie John McBride's men were superior to every opposition they faced, winning 21 matches and drawing the final dead-rubber Test in Johannesburg.
But while the class of '74 have long since been regarded as heroes by the rugby fraternity, the feeling surrounding Britain and Ireland's elite prior to departure for South Africa was very, very different.
With South Africa engulfed by the horrors of apartheid, the Lions were urged to stay away, to isolate a country floughting international decency and to say 'no thanks' to a second tour invitation in six years.
Protests dogged tour preparations, while the British Prime Minister Harold Wilson sent a letter to the Lions committee asking them not to travel. In short, the Lions were under a great deal of pressure to give this particular adventure a miss.
But while it was thought by some that allowing the South Africans to host such a high-profile sporting event would help hold up the apartheid regime, others had the opposite view. A number of the Lions who made the trip down south believed that their presence, in some small way, would help lead to political change by further highlighting black South Africa's plight.
Alongside those two distinct groups was another section of society who felt that sport and politics should not mix. For these people, sport was a separate entity entirely, one that should not become embroiled in political controversies. It was a view that was widely held throughout our game and one which was favoured by many of the 30-man Lions party that eventually flew to South Africa.
Thankfully, apartheid has now long since disappeared. The evil nature of an outwardly racist concept has been replaced by a democratic process that aims to be far more inclusive and far less judgmental. One of mans' most appalling creations is now a thing of the past.
But that doesn't mean the debate over whether the '74 Lions should have toured has now been consigned to the history books. Yes, it is now a far quieter discussion, less heated and with hindsight a companion used by both sides to complement their argument. But is still there. When the Lions toured South Africa two summers ago it was understandably brought to the fore once more and no doubt the topic will be highlighted again when the Lions head back to the Republic in 2021.
Almost everyone you ask will have an opinion one way or another as to whether the Lions made the right choice 37 years ago. But what about the Lions and the Springboks themselves? How do they view their impact nearly four decades on? Here's what a whole host of stars of that memorable tour (and one notable absentee) have had to say on the issue:
Gareth Edwards (Wales scrum-half who toured South Africa in 1968 and '74)
"By the time I went to South Africa in 1974 with the Lions, I was so much more aware of the general political situation. It could hardly have been otherwise for I encountered more and more the arrogance of the white man.
"How do I view the wider picture so many years later? John Taylor was strong enough and knowledgeable enough to say that going there wouldn't be any good at all for the future. It was his view, I respected that. Others felt differently.
"When we went in 1974, given all the fuss which had preceded the tour…we made a point of seeking out black people and asking them for their views. The majority said they thought we were right to tour, a few felt we should have stayed away. But what most said was, 'You give us the will to go on'. That will had increased significantly by the time we had finished our tour unbeaten. Rugby was the game of the Afrikaner, which is why the black people took so much pleasure from our win. It was as if we had delivered a blow on their behalf.
"How do I know that? Because Nelson Mandela subsequently made it clear that the tour worked against the Afrikaner in the long run. The Afrikaner believed he was secure in his ascendancy but we proved by thrashing his beloved Springboks that wasn't the case at all.
"I know one thing - the coloured people at the matches used to go beserk with excitement when we were winning. Even if it was only for a short period of time, you could tell that they felt a wonderful pleasure and change from their usual misery.
"It would be too presumptuous of me to say that the 1974 Lions tour caused major cracks to appear in the entire system of apartheid. I don't believe any rugby tour has the power to do that. What it may have turned out to have done, perhaps in an unexpected way, was provide one more shoulder pushing against the wall of apartheid which had seemed at one time impregnable."
Bobby Windsor (Wales hooker who featured in all four Tests)
"We played against two black sides out there and they were really pleased to play against - if you like - a white side, and afterwards have a meal together, which I thought was a great thing, both for them and for us.
"I thought by playing against two black teams we were helping. And when one of those teams (the Leopards) scored a try against us, and the Springboks hadn't scored a try in the first two Tests, well, they went crazy. It was like they had crossed the line first."
Andy Irvine (the Lions' record points scorer in South Africa)
"I did have some personal issues because I was appalled at system they ran but I also thought - perhaps naively - that sport and politics should be kept separate. We did actually play against a couple of black teams out there, we built some great friendships and, in some ways, I think we helped to break down barriers rather than create them, so I've no regrets on that front."
Fergus Slattery (Ireland flanker who played in half the 22 tour games)
"I went in the dead of night on the train on my own with a journalist from Durban up to Johannesburg. When we got there, the station master had the red carpet out. He had all his station staff lined up, as a guard of honour for us. And there wasn't a white person in sight. So, here was another extraordinary contradiction.
"If there was resentment from the black community towards us, I never saw it. They didn't have to do that. That was something that the black station master decided for himself: there's a Lion on this train. Even when you weren't looking for it, there was so much goodwill towards us, no question.
"The whole experience was riddled with contradiction. You had in those days the sections cut off from the terraces, reserved for the Cape Coloureds and blacks, the non-whites. They turned up in their droves - and some of the areas they came from were grim - just to cheer us on. If they'd wanted to make a protest in any other way, they wouldn't have gone to the game at all. That didn't mean that they were directly trying to support the tour, of course."
Morne du Plessis (Springbok back row for the first two Tests)
"Playing for Western Province on one Saturday, the coloured population would gather in the South Stand, as it used to be called, and their support was fanatical. The very next Saturday they would be cheering for the Lions. We understood what that was about and it surely troubled some of us."
Hannes Marais (Springbok skipper)
"The coloureds supported all overseas sides at that time. That didn't upset us at all. It was not a new thing.
"I don't think the tour, however, contributed significantly to the dismantling of apartheid. The pressure inside as well as outside just grew and grew. It was just part of that, but not anything special."
John Taylor (a Lion in '68 and '71 who made himself unavailable in '74)
"In '68 I was worried about the whole business of touring South Africa, but I wanted to be a Lion so much that I let myself be persuaded. I'd had misgivings but I was desperate to play. I put all the misgivings to the back of my mind.
"The prevailing rugby logic was that you weren't helping sustain apartheid, you were building bridges. As soon as I got there, I realised that was complete nonsense. There was no question apartheid was more obvious and far worse that I had ever expected it to be.
"The night before we left, the high commissioner or the ambassador said something to the effect of, 'Don't get involved in our politics; you won't understand them. But our rugby and our girls are great so go and enjoy them.' And then, when we got out there and had our first night in a hotel in Stilfontein, a group of real Afrikaaners came to our hotel and, without any prompting from us, launched into an aggressive defensive of the apartheid system and how this was the only way to treat the blacks and so on and so forth. I thought, 'Bloody hell! What have I come into?'
"Everything was so much more stark and black and white than you could have ever imagined. Apartheid then was essentially being strengthened. They were pretty much finding ways to push the blacks out of the specific areas that they wanted to. So it was really when I came back from that tour that the decision was made.
"The rugby establishment took this attitude that rugby guys were terrific guys, no matter what, that it was bigger than anything and therefore it was wrong in any way to break ranks on that. I obviously took a different point of view and thought mans' inhumanity to man was far bigger. I said I will go back to South Africa when Nelson Mandela invites me back and eventually that happened, which was wonderful.
"I was absolutely convinced that the rest of the sporting world was right and that there was this sort of massive arrogance in rugby that the brotherhood of rugby, the fraternity of rugby, meant more than the brotherhood of man - that they couldn't be bad chaps because they played rugby. It was very much that sort of arrogance that I absolutely deplored in rugby. I had no doubts at all."
J.J Williams (scored six tries against South Western Districts)
"I was naive to apartheid, but once you got out there you realised how strong it was, and how wrong it was. The most obvious time we became aware of it was when we were playing the provincial sides. We'd go into the stadium and in one corner there would be blacks, and they were all supporting the Lions. We knew then that there was obviously something very wrong; they wanted us to beat their white masters.
"I went back a few years ago and I was talking to a few officials from Transvaal Rugby Club and all of a sudden one of their guys became very tearful. I said 'what's your problem?' and he said, 'when I see you again it reminds me of all the bad times we experienced when we were supporting you. Because we were cheering, we were locked up afterwards'. Looking back at it now, we were terribly naïve."
Mervyn Davies (Wales No8 who was a Test regular throughout the series)
"In those days I was living in London and sharing a flat with John Taylor, who had been to South Africa in 1968 and was quite vociferous about his views on apartheid. We had many arguments about it but I said: 'I'm just going out there to play rugby. You've been there, now give me a chance to go there and make my own opinions about it.'"