Well that second picture might be a WW1 Royal Engineer wearing a homemade coat ... or it could be a photo of one of Genghis Khan's Mongols who somehow got slightly displaced in time... the coat would certainly fit, wouldn't it?
WRT the first photo, the shell he is sitting by is marked 38cm, which would make it what, about a 15 inch shell? Does anyone know what British gun would have fired that on the Somme in 1916? Did any RN battleships take part in the bombardment from offshore perhaps, or did the Brits maybe use excess naval guns as railway guns?
You know, as an amateur historian, I find that photo collection absolutely appalling. Things like a whole series of photos of the London Scottish Regiment in 1914. No other photos of the regiment are known to exist from WW1 - or at least from early WW1 before the first version of the regiment was pretty much wiped out in the early battles.
And these ones only exist now because back in the 1970s, this garbageman noticed them as he was emptying a trashcan into the back of the compactor truck and rescued them from being mashed up and dumped in the landfill.
Just like everything else in his collection - 5,000+ WW1 photos plus letters, memorabilia and God knows what else -- all thrown in the trash heap instead of being sent to the National Archives or the Imperial War Museum or any one of a number of regimental or local museums or archives.
People are uncaring idiots sometimes about history, aren't they? ... But then you also have the occasional one like this garbageman, who noticed an old letter going into the garbage, opened and read it, realized it was that soldier's last letter home before he was KIA and decided that sort of thing shouldn't just be going into a landfill. So he spent the next 30 years trying to save what he could.
Of course nowadays, with the automated forklift trucks that dump the bins, nobody would ever have a chance to notice this stuff in the trash...