Members of the National Union of Teachers (NUT) are launching a campaign of action short of a strike, joining those in the NASUWT who are already taking action.
Industrial action by teachers over issues including pay, pensions and workload will be stepped up today amid warnings of an escalation in the coming months.
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The Labour leader did not say whether he would maintain Britain's nuclear deterrent programme.
Ukip leader Paul Nuttall also said he would want to get rid of Sharia courts.
Over 40,000 people picked up their packs to take part in the annual marathon in the capital.