Power Pole ground to iron grill connector
I use cad weld when I need bonds that will stand up to anything or I do not want to have an access hatch for the bond to be inspected. Looking at the mess at your weather head you may not be able to find an electrician that can do it. The graphite trays that contain the metal are two expensive for the homeowner, but you may check around. Cad welding is an exothermic bonding that will bond copper  to rebar , steel pipe and even zinc &amp; copper. 
With wrought iron after cleaning the area you might consider a deox or noalox anti oxide compound this will prevent rusting at the contact points.