The end result of the British policy was the holocaust.
"Yet there are considerations which even the most heartsick Zionist cannot ignore as he sees his hopes circumscribed -- hopes that have developed to comprise an ever-expanding national state and a great experiment in collective living.
"As understood by the Zionists, the Balfour Declaration supported these hopes. Just as certainly the Arabs were led to believe by the McMahon correspondence that they would possess and rule the land."
"It is true that the cases of both peoples rest on contradictory promises. But it is also true that the conditions and assumptions in which these pledges were given and taken obtains no longer. The world of twenty years ago does not exist."
So says the NYT. But of course, it did then, and does still, to some degree.
But the key point here is that the NYT, along with Arabs of that time and this, misrepresent what those 1915 McMahon correspondences were all about.
The question was British support for Arab revolt against the Ottoman Turk Empire. The Brits agreed they would support the revolt (remember Lawrence of Arabia), and the result would be a set of independent Arab countries in all former Ottoman areas except those "portions of Syria lying to the west of the districts of Damascus...".
Beginning at least by 1917, with the Britain's Balfour Declaration promising a homeland for Jews, Brits insisted that "west of the districts of Damascus" included Palestine.
Here is Churchill's argument on it in 1922:
"That letter is quoted as conveying the promise to the Sherif of Mecca to recognize and support the independence of the Arabs within the territories proposed by him. But this promise was given subject to a reservation made in the same letter, which excluded from its scope, among other territories, the portions of Syria lying to the west of the District of Damascus.
"This reservation has always been regarded by His Majesty's Government as covering the vilayet of Beirut and the independent Sanjak of Jerusalem.
"The whole of Palestine west of the Jordan was thus excluded from Sir. Henry McMahon's pledge."
In 1933, McMahon himself wrote supporting this interpretation and stating further:
"I also had every reason to believe at the time that the fact that Palestine was not included in my pledge was well understood by King Hussein."
Finally, we should note that Arab revolt against the Ottoman Empire was not successful, until Britain in 1918 sent more than a million of it's own Empire troops to the Middle East to finish the job. So in the end, the Arabs got more than they bargained for, while contributing far less than originally understood. So their claim to being "promised" Palestine is false on two counts.