This is not an unknown piece as all 4 pages are reproduced in Milbourne Christopher's Houdini A Pictorial Life. However, what's makes this one so exciting--apart from it being an original--is it contains a smaller tipped in program for the patriotic playlet "Soldiers of the Queen."
"Soldiers of the Queen" was a feature of the Alhambra bill when Houdini made his debut there in July of 1900. That suggests this is from Houdini's famous two month breakout run at the theater. "Soldiers of the Queen" was still playing at the Alhambra when Houdini returned in December, so it's possible this comes from that later engagement. But the play left that month, so this can only be from 1900. That makes it a pretty exciting and significant piece of early Houdini history.