Unite the Union members working in six schools in Hackney will be taking strike action on 30, 31 January and 1, 2 and 5 February as part of a campaign to win fair pay and decent contracts.
The employers, OCS, are subcontracted by Kier, which has a contract with the council to clean schools.
OCS have stated that they want to force all staff who remain on year-round contracts onto term-time-only contracts. They argue that staff should not be paid for when schools are closed.
Unite previously won a fight to get the workers' pay raised from the minimum wage to the London Living Wage. Now OCS are refusing to pay the new uprated amount that was announced last November.
The union response - to call for five days of strike action - has got the attention of the subcontractor, contractor, council, mayor and the Labour Party!
Up until the point of issuing the strike notice, nobody was talking to the union. Collective action certainly gets you noticed! The union is sticking to its position - the strikes are on until the members accept any offer.
Unite regional officer Onay Kasab said: "We have been approached by the employers and asked to call off the action - yet no offer has been made.
Unions now have to jump through hurdles to secure a legal ballot so having made all that effort, why would we call off action when no offer is on the table? Our members voted, with a majority of 100%, for strike action. If the employers do not make an acceptable offer we will strike."