Thanks everyone for the comments.
don't worry about the Deus not finding it its just that you never went over it
Oh yes I did. At least 3 times. And from different angles.
The problem was that the area was full of junk, foil, bottle tops ect and the Deus was giving signals all the time despite me playing with the discrim and sensitivity.
Probono.
You asked about Etrac settings.
In the discrimination settings I blacked out the whole screen then waved a few gold rings over the coil and used the accept/reject button to accept only them signals. ( Minelab call this "Auto latch mode" pg 48 in instructions).
It finished with a black screen apart from a small white line at 12:07 to 12:30.
I used Deep off. Fast on. Trash High. Ground difficult and turned the sensitivity down to 15.
The detector was then very quiet and ignored all the junk and deep stuff.
I had 2 signals that were bits of rolled up foil just in the surface then 3rd signal...BINGO.