+1 to the above.

Special needs people usually need a custom design. Calfee built a couple (or more) many years ago, I have also seen custom machines and custom wheels at 2 other factories.

The Mercian frame would seem to indicate a Frenchman might want a unique type of ride, but in fact the only place I have seen this design (2 wheels in front with traditional diamond frame) was in Zurich around the lake. He was going about 5 or 6 mph and looking quite dapper on a sunny summer day.