Box made a nice animated GIF that shows the process very well. It may not be obvious in his clip but the first intersection results in a hole as evidenced by the profile edges around it.
I use this process of copying or cutting geometry to the clipboard and then pasting it in place inside components in almost every model I draw. I use Edit>Paste in place enough that I created a keyboard shortcut.
Thanks to all for your assistance. Had to do a design work around due to time constraints. Will have a play with all suggestions when I get time. Interesting technique, Dave, Never would have thought of that!
Cheers