John McDonnell, the shadow chancellor, endorsed a Marxist pamphlet which said that the working class needed to be "armed" to take on the police, army and security services.

In 2011 Mr McDonnell wrote the foreword to a pamphlet by the organisation Permanent Revolution, hailing it as "timely" and calling for a "climate of resistance" to bring the Coalition Government down.

One chapter of the pamphlet, entitled "the revolutionary road to the socialist alternative", calls for the establishment of a "workers' Government" which would "take over ownership of production and services".

The leaflet, highlighted by the Guido Fawkes website, says that the new Government could only come about through a "revolution" and would be met by "fierce and violent resistance by the ruling class".