Short answer: look for droppings, scratching, gnawing, greasy marks, disturbed food, smells and repeated activity around pipework or bin stores.
Why entry points matter
In London buildings, pests often use service gaps, older brickwork, basements, lightwells and shared waste areas.
What not to do
Avoid disturbing suspected nesting areas, leaving food accessible, or sealing every hole before a survey if active rodents may still be inside.
