Homeowners living on the River Lea in Upper Clapton are furious after councillors approved plans to convert a garage into an ice cream shop.
The garage, or boat house, as it was originally, is in Watermint Quays, and fronts onto the towpath.
Neighbours opposed the plans, saying there is already strain on their infrastructure and opening a business would make things worse and strip away their privacy.
They also argued the terms of the lease state properties must not be used for commercial purposes, and now think others will try and do the same.
"The councillors did not properly address the objections about traffic, parking and waste and were not made aware that WQ is a private, residential road," they said.
Councillors on the planning sub-committee denied a precedent had been set, saying any future proposals would be viewed independently.
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