Andy Wightman, housing spokesperson for the Scottish Greens, said it was “hard now not to notice” the number of key boxes appearing on the front of tenements in Edinburgh.

He added: “Drilled into doorways or stonework entrances, the increase in the number of these unsightly additions simply reflects the number of residential flats that have been converted into short-term let businesses.”

The MSP has published a new briefing paper which suggests that some short-term let operators may be attaching key boxes to the exterior wall of a flat “he or she has no ownership of”.

The briefing paper continues: “This is known as an encroachment in Scots law and is interpreted as a permanent or quasi-permanent intrusion into property, which is owned or lawfully possessed by someone else.

“This can be remedied, as a last resort, by civil court action. Individuals affected can physically remove the box in question in certain circumstances. However, this comes with a heavy caveat with obvious risks attached; including the possible effect on relationship between the neighbours concerned and the fact that a court may later disagree that there as an encroachment.”