Distribution of Political Leaflets

Good evening all.  I need some advice as this evening 2 strangers appeared on our landing wanting to distribute very political leaflets to individual doors.  I asked them if they had permission and they told my a resident had asked them to do this.  They then immediately left. 

My question is, and I know at the time of local elections, and General Elections we are bombarded with political leaflets.  And, this is I believe by permission from the City of London.  However, this was entirely different, and I would like to know if an individual resident can give permission for very political leaflets to be delivered around the Estate, without the knowledge of the City Corporation.  

Thank you.