People angry about a legal loophole which means a mobile phone mast can be erected have held a protest.
Protesters will lobby Hackney Council on Monday
Hackney Council refused planning permission for the mast, but as T-Mobile was informed of the decision too late the project can go ahead.
In the past seven days campaigners have twice managed to turn diggers away from the Richmond Road site.
The council blamed an administrative error for the situation and said it had a meeting with T-Mobile planned.
Julia Horsfall, who lives near the proposed site, says she is "furious" about the situation.
She said: "We weren't consulted about this. T-Mobile said it went through its procedures but we simply didn't know.
"The council refused permission and we thought that was the end of the mast, then barely a week-and-a-half ago T-Mobile arrived to put the mast up.
"It's not the only one in Hackney. We discovered that in Shepherdess Walk, in Hoxton, exactly the same thing happened.
"The council was two days late and T-Mobile are trying to push it up."
Hackney Council said it had "fully intended" to block the mast and was hopeful that it would be able to negotiate an alternative site at the meeting with the mobile phone firm.
The statement said: "Unfortunately due to an administrative error we failed to formally stop this application being granted within 56 days as the relevant legislation requires. As a result planning permission has been granted by default.
"We will be investigating how this happened and are concerned that T-Mobile has not to date accepted this unfortunate mistake when there is clear opposition from both the council and residents. "
A T-Mobile spokesman confirmed that they would be discussing alternatives with the council at a meeting on Monday afternoon.
He said: "As always we are going to be as flexible as possibile to find a mutually acceptable situation."
Protesters were due to lobby the council on the steps of the town hall, in Mare Street, and schoolchildren were to join a demonstration at about 1600 BST at Dorothy Hodgkin House, in Reading Lane.