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Hello, my name is ***** ***** I will try to help you. Please remember I just report or interpret the law, so the outcome may not be what you hoped for.
There should be no restriction on you installing a safety latch of the type you envision. The landlord only needs to gain access in the case of an emergency when you are not in the premises. The type of latch you are talking about only is use when you are in the premises. For this reason you should feel free to install the latch.
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