Somehow I managed to miss this during the whole "Tonight Show" mess with Conan and Leno but here is a cool article that describes some differences in UK and American TV viewing audiences.
Basically, there is nothing like Leno/Letterman/Conan/(Lopez?) in the UK. Nothing that is five nights a week with guests and interviews and music. The article states that the guests would be scarcer which is actually probably true. There would probably be one or two A to B list British celebrities a week and then the other nights would be filled with Z list wannabes or obscure people you really don't care about....aka Z list celebrities.
There probably is a market for it..maybe at the 6:00pm time slot or 8:00pm...the "After tea" time slot (tea the meal not the drink) because I actually really enjoy Letterman and enjoyed Conan too but they were both on late. I think one aspect that would turn off British viewers would be the depth of the interview. Most of the time with the talk shows here you can almost predict the questions:
"How's your family doing?"
"Now, you just for back from "INSERT LOCATION HERE" how was it?"
"You had a bit of trouble on the Flight/Car ride/Taxi recently didn't you?"
And then when we are about to discover something interesting or take the conversation to another level, its:
"Tell us about your latest movie/TV show/book/hand puppet"
Which is all we have time for because here comes a commercial.
That said, I am looking forward to Conan on TBS.