Last Friday a photo of men from the Portsmouth Home Guard was published. They seemed to be holding some bomb making materials but this was just an educated guess.
I have received an answer as to what was actually occurring
The white coiled stuff being held by the chap in the front row, and the one behind him on his left, is Cordtex or instantaneous fuse – which could also be used as explosive for very small jobs.
The box he’s sitting on is a bit large for a detonation generator and looks a bit posh for a box of explosive, although I may be completely wrong.
The coiled stuff being held by the chap on the far right of the picture may be a safety fuse – burns at a foot or so a minute and could be lit from a cigarrett.
It could be that the Home Guard were being trained in blowing up bridges to slow an invader’s advance rather than in bomb or mine making.
A very old friend of mine who was a Royal Engineer and he recalled his unit being posted to defend Portsmouth, and being billeted in one of the forts on Portsdown Hill.
His chief recollection was that the unit based there before them had left a load of explosives in the fort’s magazine, which were very badly stowed together with detonators.
The REs had a sleepless night, expecting the whole place to migrate skywards, before they could get at it and re-stow to RE standards.