The Scaffold were a comedy, poetry and music trio from Liverpool, England, consisting of Mike McGear (real name Peter Michael McCartney, the brother of Paul McCartney), Roger McGough and John Gorman.
If any passing reader has listened to the above song and wonders, "what's the Aintree Iron?" Nobody knows for sure. Numerous possibilities have been provided by commenters HERE, there's even a comment from Mike McGear/McCartney bimself; but by the end of the thread one is no nearer to knowing the truth. As Aintree is the part of Liverpool where the famous horse race course is located, I suspect Aintree Iron relates, in some way or other, to that.
Anyway, my own "thank you very much" goes today to all who read and/or comment here - y'all are much appreciated!