Possibly. The Merc has an aluminium frame and makes a reasonable boat anchor.
The local Brompton dealer has a theory that they're working on a titanium frame (the current "titanium" Bromptons only have a Ti fork, rear triangle, seatpost and (of all things) mudguard stays. He claims to know Andrew Ritchie, so there may be something to it. How you weld a Ti tube to a cast iron hinge, I have no idea.