Let me see the rest of the properties for your combo box. Also see List Items Edit Form.

Thanks Richard. I attach an image of the Combo Box properties, and of the properties from the source table.

Sorry, I'm not sure how to upload the images for this reply.
Stephen

Use the same link as before (in your original post).

Upload

Thanks Richard and Kevin.
Stephen

What is prompting you "Do you want to edit the items in the List?" I've never seen that before. When you set a list items edit form, it just opens the form. It doesn't ask you anything. See Access Beginner 8 or this Extended Cut video: Relational Combo

Hi Richard, yes I've studied both Beginner 8 and the Relational Combo but can't see a solution. I don't know the answer to your question about the prompt. I've tried again, unsuccessfully, to amend the "Limit to List" property of the combo box. I'll attach the screen shot of the response.
Thanks,
Stephen

Stephen,

You shouldn't need to change the Limit To List property to NO. When you click on your Combo Box to open it, an icon should appear below it. Click on the icon to open your List Items Edit Form.

Thanks Kevin. Yes, the little icon presents itself - see image - however, when I click on it nothing happens - it just disappears and it won't allow any edits/additions.
Stephen

Check the properties for your form. Allow Edits should be true.

Thanks Richard, I've checked the form properties. As per the next picture, the "Allow Edits" is "Yes". I changed it to "True" which it accepted, but the combo box still does not allow additions. When I checked the form properties again the value had reverted to "Yes".
Stephen

I have  a suspicion based on the error message that your ID field is not the first field you brought in when creating the combo box.  Its saying "...isn't equal to the the bound column."

Would you click on the Format tab and look there please?  Change any 0 (zero) in the widths to a positive number. Mine is in inches but I believe yours will be cm.  Also temporarily turn on the header by changing Column Heads to yes.

Now go back to Form View and click the drop down for your combo box.  Screenshot that for me if you would.