Is the full name of et3 an Ermini 357 Sport, from 1955?
Nope.
What about an Ermini Sport Competizione 1100 then (also from 1955)?
It's not what I'm looking for. There is a name missing, the name of the person who built it.
I've spent a lot of time trying to find more out about this car. It's actually pictured on numerous sites but is always simply captioned as an Ermini Sport Competizione 1955, obviously because that's how it's entered into events; but I know it's not actually an Ermini!
It seems that the frame was originally built by a mechanic called Righini and differs completely from the normal Ermini frame. At some stage (whether originally or not I don't now) it was fitted with a Type 114 Ermini 1100 engine and was given the body which was actually the first Frua body fitted to an Ermini 357 (see picture below of it back in the mid 1950s).
Other than that I haven't been able to find anything else out (but I am still looking!)