To save hijacking the other thread too much I'll move this to a new one. I emailed details of my lamp to the manufacturer who replied "That is a Type No.1 but as you say it doesn’t have the normal label attached. Im curious myself as I have not seen one like this before. It could have been made for a colliery surveyor as it is brass but it shows no sign of any use." I took the lamp apart and it's got all the gauze and bits that suggest it was made as a working lamp. No sign that it's ever really been used though. I guess it's off to the museum next to see if they know anything about it.