A one hour delayed ITV1 can now be found on Freeview Channel 33 - started on the 11th to a fanfare of silence, so you may not be aware that it is available. +1 channels can be most useful when two channels clash with your faves.
You may need to do a retune, or indeed not. My TV just silently added it, my Freeview recorder box didn't - I had to do a rescan and then it appeared.