You should only let someone in to your home if you’re absolutely sure that they’re genuine and you want them in your home. You don’t need to open the door for them and don’t feel embarrassed about turning them away.
Be wary of bogus callers who try and trick their way in to your home by pretending to be a meter reader, police officer, council official, or an ordinary person needing help. You can ask the person to come back another time when someone you trust will be with you.
If you’re worried about a doorstep caller, dial 999 and ask for the police.