The New Zealand 2-3-2 scrum formation caused controversy from the moment it was first seen in the Northern Hemisphere in 1905. Matters came to a head with the Lions tour to New Zealand in 1930, which, according to the tour agreement, was to be played under International Board laws.
“..... manager James Baxter's crusade against the hosts’ habit of fielding a two-man front row and a wing-forward deployed outside the confines of the scrum led ultimately to a change in the laws and the outlawing of this practice.
[…, post: "]
He also ensured he had the final word, courtesy of the trump card of his position as England's representative on the International Board, the law-making body of which New Zealand had not been allowed to become a member.
By coincidence or otherwise, within a year, the board had adopted new regulations requiring teams to field three men in the front row of the scrum. At a stroke, the 2-3-2 formation and the wing-forward was consigned to history. Baxter's mission was accomplished”
(The Lions. The Complete History of the British and Irish Rugby Union team
by David Walmsley)
This is pretty well what all the histories say, though some phrase it less aggressively – which is apparently more than you can say for Baxter. However when I was in the RFU Reference Library at Twickenham a while back I decided to look at the laws in question.
Before 1930, there was no mention of the number of players in the front row. In 1931
[1] there was indeed a change, but it merely specified “no more than three”. That certainly does not outlaw a two man front row. Indeed the minute books of the RFU (which also included the minutes of the IB meetings) make it clear that this phrasing was deliberately designed to accommodate the New Zealand formation.
In 1933 the RFU proposed changing this to requiring precisely three on the basis that New Zealand had now adopted this formation as well, but the IB decided not to make any changes at that time. In fact it was not until 1950 that the law demanded a three man front row.
One of the more cautious histories has a subtler version:
Centenary – 100 years of All Black Rugby
RH Chester and N A C McMillan (1984)
“…
James ‘Bim’ Baxter …. obviously had great influence in the halls of rugby power and it was speculated that while in New Zealand he would lay the groundwork for the outlawing of the wing-forward position. This came about indirectly with changes to the scrummage off-side and hooking laws. New Zealand was disadvantaged to such an extent that in 1932 the NZRFU annual meeting decided to adopt a three-man front row and abolish the wing forward position.”...