Suggested from here, where it is noted:
The original language of the declaration that was approved by the British foreign office and Prime Minister Lloyd George on September 19, 1917 specifically stated that Britain accepted the principle that "Palestine should be reconstituted as the national home of the Jewish people."
Use of the term "reconstitute" meant that the land was once their homeland before and should now be restored to them. It meant that the Jews had historical rights. For that reason, this language had been sought by the Zionist leadership led by Chaim Weizmann and Nahum Sokolow who wanted it indicated that the Jewish people had a historical connection to their land. This original formula had been approved by President Woodrow Wilson, to whom the text was submitted in advance.
It was not such a far-fetched goal to seek formal acknowledgement of Jewish historical rights. A little over two decades earlier a well-connected Protestant clergyman from Chicago, Reverend William Blackstone, received broad backing for a petition for a Jewish homeland signed by the chief justice of the Supreme Court, the speaker of the House of Representatives, university presidents and the editors of The New York Times and The Washington Post. Top industrialists, like John D. Rockefeller and J. P. Morgan, also lent their support. In short, the idea of the Jewish people re-establishing their country had become acceptable in the elite sectors of the American establishment.
Blackstone's petition specifically characterized the connection of the Jewish people to Eretz Israel as "an inalienable possession from which they were expelled by force." In other words, the Jewish people had not willingly given up their claim to their land. Indeed, there was no act in which they relinquished title to the Romans or their successors;