How to display Key (Guid) of element in block's editor settings - Editor Appearance - Label field

I am on Umbraco 8.

I want to display the unique Key (Guid) of each element of a blocklist in the label field of the blocklist element.

My blocklist element’s data type has a property with alias itemName. So having this AngularJS expression in the “Label” field in “editor appearance”:

{{itemName}} 

displays the item name in the blocklist element list just fine.

The data type also has an inherited Key property. But when I change the expression to

{{itemName}}, Guid: {Key}

nothing is displayed for Key. Same when I use key.

Is there a way to display this inherited property through an AngularJS expression in the backoffice?

Background:
I have a blocklist, and I want to be able to address specific blocklist elements from code in a view file. I thought it is a good idea to use the unique Key value of the blocklist elements for this. If there is a better way for this, I am grateful for hints.


This is a companion discussion topic for the original entry at https://our.umbraco.com/forum/105785-how-to-display-key-guid-of-element-in-blocks-editor-settings-editor-appearance-label-field