Let me start by saying I have no clue. Guesses, yes, but knowledge, no. At various times Sasieni, GBD, Parker, Comoy and a number of others used the phrase London Made. A little more to go on might possibly help. For example, is the London over the Made? Or in a straight line? Or arched? Is the font block or cursive, with or without serifs, all caps, etc? Is it possible to show a picture? And is there anything stamped on the stem, top or bottom? Is the button opening orific or a slot? Can you show a shot of the tenon? Is there any hardware inside the pipe?
None of this would be, even if available, necessarily dispositive, but any additional info whatsoever might be helpful. You never know.