Obstructing my basement firedoor

[Guest Wendy Benn]

I have a basement kitchen in my private home with an inward opening door and an outward opening security gate aswell.  People constantly park their cars right up to the gate so I can't open it and I've put signs up and left notes asking them to stop but it hasn't worked.  Can I got the police or the fire safety office involved and are they able to stop them parking there as I am worried that my children wouldn't be able to get out of the house if they were in the basement in the event of a fire. 

[Tom Sutton]

Are we talking about a single family domestic premises or are they flats and are they parking on the pavement?