Recumbent bikes/trikes and C5s have a common (very serious in my view) safety flaw which is they have a very low visual profile at the eye level of most drivers, which makes them (I think) really hazardous in dense city traffic. The first thing your average West London driver taking their kids to/from school, ballet classes, drama club etc would see of a recumbent bike of any kind is when they had already gone under the wheels of their gigantic Chelsea tractor.
I don’t think I’ve even seen a recumbent cyclist in real life without a high red or neon yellow flag on the back of the bike, presumably for exactly this reason.