153-ball double century
... that Nathan Astle's 153-ball double century is the fastest in Test cricket?
... that <a href="./Nathan_Astle" id="mwDK8" rel="mw:WikiLink" title="Nathan Astle">Nathan Astle</a>'s <b id="mwDLA"><a href="./List_of_international_cricket_centuries_by_Nathan_Astle" id="mwDLE" rel="mw:WikiLink" title="List of international cricket centuries by Nathan Astle">153-ball double century</a></b> is the fastest in Test cricket?