Yes, Fudge Cycles in Kensal Rise, London is another shop that cold sets Brompton triangles, but you have to be used to working with Bromptons to do it right, which isn't the case for the bike maker over here who never worked with them, and who'd rather braze new dropouts.

Based on how a Brompton folds — the rear wheel pushes against the seatpost to keep the whole thing closed —, I'm concerned bolting new dropouts to the existing ones might impact the fold by adding ~1-2cm to the wheelbase, but I'll certainly suggest the idea. Thanks!