Thanks, I have now modded it further (3 hrs last night in the LR with a lead lamp held by my son, freezing cold) I have made a bracket out of alluminium and sprayed it satin Black and mounted the sat-nav unit onto the dash to the right of the stereo (left of the speedo binnacle)It can't be seen by passers by looking into the window now (at least from the sides). I bought a sat nav aerial and mounted it on the wing top and routed the cable through the bonnet (the gap underneath) then into the engine bay and through the grommet for the bonnet catch on the bulkhead and into the interior. Then I routed it up behind the fascia again, using a bent wire coathanger made into a hook and into the back of the sat-nav unit.
It's been a lot of phaff but it's neat and tidy and no wires showing now. It does look like a proffessional job now.
If anyone wants to do similar I would be glad to send photos or more info.
Tim