Now you can pull forward the centre section of the dash, once you have ondone the two screws under the ashtray:

This centre section is just clipped in at the top and will pull out with a little force.

You can disconnect all the switches, but I found you only needed to pull it out a couple of inches, and there is enough slack in the wires for this. This will reveal two screws holding the upper dash panel in - remove these screws. Also remove the three above the instruments in the cowl, and there are a couple on the underside, each side of the steering coloumn - but note, there are a few screws here, it should be clear enough which ones need undoing...
The lower edge of the dash should feel a bit loose now, but it will be still held in by the clips along the top. These clips are wedged onto a plastic spur that is part of the dashboard panel, and there are two options for removal. (Well, three if you include my initial method "ripping", but that was a tad bit destructive..). Easiest is to look at the final photo, showing the clips set up ready for the dash to be refitted - if you can get them out like that, that's great, and it takes a small screwdriver to push down the metal tab as the dash is drawn forwards.

Or you can try and release the clips from the dash mounted plastic lugs, with a thin, hooked, pointy thing.. But most of mine came out like this:

This then presents you with four very obvious screws left to undo in order to remove the old stereo (as seen below)

and this is why you were never going to get the radio out with the usual pair of screwdrivers.. The brackets on the old radio will need to be transferred onto the new one [Note, these little screws were screwed incredibly tightly, and only came out using a cordless powerdrill / screwdriver thingy. Even then, one had to be drilled out - to the detrement of the health of the old radio..] Revealing the Nissan connectors:

I have no faith in my soldering ability, and so I took the much more popular option of a harness adaptor from Halfords, for about a tenner.

The remaining aerial connection is a Japanese standard and looks nothing like a UK plug - but this wasn't a problem on my car as the final inch or two of the cable could be pulled off (there was a connection wrapped in foam) to reveal a std Euro type plug. Robert is your mother's brother, in true Hynes manual style, refitting is the reverse of removal. Just be sure to wedge all the bits of wire back properly when you reassemble the dash, waggle all the heater controls about before you put your tools away (my heater control won't go all the way to 'cold' since I must have got a wire trapped..) and enjoy.
Now what did I do with all the photos..?