There's no guarantee that a new field will appear on ANY layout in your database and this is true for the latest version as well as 7. If you investigate preferences settings for this database, you'll find an option for automatically adding new fields to the current layout. If this preference is not specified, no new field is automatically added to any layout. Since this preference can alter the size of layout parts and pretty much never puts the new fields where I want them, I prefer not to have this preference selected when I am developing.
You can add a field to a layout by entering layout mode and then drag and dropping the field tool--it will appear lower down in the secttion shown in your screen shot once you enter layout mode. A dialog will pop up where you can select the filed that you want to add in this fashion.
Many thanks Phil.
Understood about variability when creating new fields.
Tried as you suggested and inserted pre-existing field into layout using layout mode.
Meant to say I tired and it worked. Thanks again, nick.