Both Herse and Singer were not exclusively "lightweight" single/ tandem/triple builders. For example, both jumped on the proverbial French tax-free motorised transport bandwagon and produced Velomoteurs in the early 50's by strapping petrol (gasoline) engines to their products. These were seen at the Paris Show (Singer 1951 & 52 & Herse 1951 only). Herse also displayed at one show his finest "dreadnought" roadster...... Don't forget these guy's were first and foremost businessmen not classic enthusiasts and certainly wouldn't have been slow to produce a trike had there been a demand or a customer. So who knows maybe that trikes out there somewhere - what with using Reynolds 531 and Brooks saddles all they needed was the Holdsworth kit ! I'd make your first port of call to find Herse's daughter if she's still alive - she was an accomplished randonneur herself....
I've got a vision here of Dennis Hopper on an all-chromed Herse frame with a V-twin strapped to it !
The 1954 show report also mentions the Peugeot "special course" PLX10 racing Model- a bargain at at ff.35,000 - almost half the price of Herse's 15-speed "randonneur" Little wonder the crowds were happier following Louison Bobet round the show than picking up Rene's latest product !
Postscript - Very few French manufacturers didn't turn out a "velomoteur" of some sort - in fact some almost exclusively though notably Pelissier and Peugeot were amongst those that didn't, both saying that it was just a fashion - and both fortunate enough not to go under through lack of sales and unsold stock they couldn't shift.
Au revoir (yes I know Sheldon my French is doubtful)
Bob Reid Stonehaven Scotland (you know - that place north of England, where there are absolutely no cycle jumbles, Dale.)
The Flying Scot Website - http://freespace.virgin.net/