The drain pin is missing. It is the gully at the bottom of Mornington Street (unmarked on your map) outside the side entrance to no.33 Arlington Road

This gully in Mornington Street blocks frequently. The problem has been reported many times previously (12/07/21, 5/10/21, 15/12/19: three examples). As the gully is at the bottom of the Mornington Street hill, and takes overflow from Albert Street too it receives a lot of water. Before the table junction was installed it could flow away down Arlington Road but now it can't. When it blocks it is impossible to get in and out of the front door without wading through the water, and also the water ends up flowing into a basement lightwell and could end up causing a flood in the house. In 2021 it was agreed that an additional gully would be provided here but this work has not been undertaken yet. I would be grateful if you can take another look at this!