In response to my request for information on the above, Jeremy Banning brother of GBG member Mark Banning has provided the following information. He has been involved in the search for the Flamethrowers or more properly called the Livens Large Gallery Flame Projector.
The project to excavate the site was five years in the gestation with pace picking up in the last year. It involved countless meetings with local museums and authorities as well as six months archival research
Organised through GUARD (Glasgow University Archaeological Research Department) who did the initial work at Fromelles and the excavation of the Vampir Dugout in 2008, it was financed by a variety of British, Canadian, French and German broadcasters who contributed to the costs. The dig was filmed throughout by a Canadian TV production company, Cream Productions who made 'Digging up the Trenches' as well as the 2008 programmes on the Vampir Dugout.
An international team included Dr Tony Pollard (GBG member) and Dr Iain Banks from GUARD and two of their PHD students. Also including were French archaeologists and serving Royal Engineers. Safety underground was in the hands of two highly experienced men from Mines Rescue UK.
The necessary clearances were obtained from the relevant authorities and local landowners. The project had the full support of the Mayor of Mametz, the Historical in Peronne and Alain Jacques head of the Service Archeologue Municipale in Arras.
Four Flamethrowers were to be used in the southern Somme sector on the 1st July 1916. Two were successfully used where the lines crossed the Carnoy-Mountauban road. One at Kasino Point close by was knocked out of action before the battle started and the fourth one was in position between Mansel Copse and Bois Francais.
The one near Mansel Copse required a working party of 300 Devons to bring the Flame Projector up in pieces to the front line where it was re-constructed in a shallow mine gallery running under No Mans Land. However this Projector was damaged 'beyond recall' during intense German bombardment of the British Lines on the 28th June.
Each Flame Projector weighed 2.5 tons and required 250 man hours to be brought from the rail head to their respective saps. Once in position they took six hours to be constructed by a six man team. They would lie under the ground with the 'monitor head' breaking the surface when the machine was activated. It could spew out a ton of 'heavy and light oil' in a ten second burst over 100 yards away. This could be repeated twice before the Projector ran out of fuel.
The object was to terrify the enemy and to enable British troops to get across No Mans Land unscathed. The fire would keep the enemy heads down - the smoke would obscure their visibility.
The BBC filmed the site for a news item
http://news.bbc.co.uk/1/hi/also_in_the_news/8691705.stm
Subsequent research by Jeremy Banning who works with Peter Barton on books and archaeological projects, showed that one of the attacking battalions on the 1st July 1916, 2nd Borders 'only' suffered two casualties whilst crossing No Mans Land. However they suffered considerably greater losses once they got into the German trenches.
Peter Barton has written a book entitled 'The Somme - a new panoramic perspective' with all the detail of the dig. Currently out of print the intention is to get it reprinted for early next year.