Somme maps/aerial photos + trench overlays ?

[dah]

From time to time, I have seen some wonderful modern maps and/or aerial photos on this site with overlays of trenches from 1st July (and other key dates)

I'm off to the Somme next week - and it would be a great asset to have some of these to assist my meanderings around the various Somme areas

I have the standard IGNs for the area - but find these + the umpteen books I have to carry to get my bearings incredibly cumbersome and inefficient.

If I had the time and money, it seems that 'Linesman' is the product to have...but, on this occasion, time is definitely against me.

Can anyone help with appropriate web or forum thread references or map/photo postings on this site. I've tried various searches without a lot of luck so far.

Thanks in anticipation.

David