A couple of years ago, my friend and neighbor Paul published a web site covering pre-decimal booklets, including the Sterling Machins.
He has now added a site for pre-decimal stamp rolls (generally called coil stamps here in the US). The complete range of coils from the Downey Heads to the Sterling Machins is included. You can go right to the Machin page here.
He is looking for one image to complete the site: the AE coil leader for the 5d Machin. If you have an image he could use, contact Paul directly using the contact link on his site.