Why would you support Zionists and Communists against Fascists? by Jay Knott (01/30/13) ⇌ (Crisis in the Socialist Workers Party)
Tony Greenstein is an anti-fascist campaigner in the UK.
Here, he reviews a book about the history of fascism in Britain (it's quite a small book). He takes for granted that it is justified to form united fronts with communists and Zionists to oppose fascists.
The first and last of these factions have reason to oppose each other, and the second, being Jewish, has some reason to unite with the first against the third.
So why should one support Communists and Zionists against Fascists?
If Greenstein has an explanation, he doesn't give it.
Another oddity about his review is his unusual definition of "Zionist":
"Most British Jews then were not Zionist, although they supported the establishment of the Israeli state".
Wikipedia defines "Zionism" as "a form of nationalism of Jews and Jewish culture that supports a Jewish nation state in the territory defined as the Land of Israel".
So how they could support the establishment of the Jewish nation state in Palestine without being Zionists isn't clear.