Hmm.. Just went out to look, and yes! The switch doesn't close. It's for the fuel injection, to let it know when the throttle is closed. It doesn't appear to have affected my car, perhaps a slightly poorer fuel consumption, but I haven't noticed that if it's the case. I'd rather have to nice throttle response anyway, which I get. What you want to try is up to you.
By the way, you'll find pics of the racing 190s you talk about on my site here:
Unfortunately, there's no underbonnet pics :-(
I'm near to Dursley, in Gloucestershire, but am sometimes in Bristol too. Next week I'll be in New York :-)