I had a "membrane strip" done by my OB in my last pregnancy. I kind of assumed they were the same as the "sweeps" the UK women refer to, but now I think mine might have been a bit more invasive (for lack of a better description).
My doctor was certain it would work quickly, even said, see you tomorrow...I was in labor hours later, and I did see him tomorrow, to deliver.
Mine was painful and his finger was way inside my cervix. I read somewhere a UK woman said a doctor came in while she was on the labor ward and gave her what he referred to as a "good sweep," which she described differently from her others. So I'm thinking this might be more along the lines of what my doctor did.
All that to say, mine definitely worked. I was 1 cm and hadn't lost any of my plug as of my appointment. I left with my plug falling out, spotting/show and was contracting within the first couple hours. It worked for me!