Who? (that would most likely be a "no" then
Did it with my BSAC club, Northwest Divers (BSAC 1004) based in Manchester.
We took 3 boats down (2 RIBs, one speedboat), and only 1 of the RIBs got away from the slip as the gears on the club's boat decided to stop working, and then the speedboat started having engine troubles about halfway through the day. Luckily I had got on the working RIB from the start, so didn't have any problems!
And, for the amusement of the others in the group, I found the end of the slipway, by walking straight off it. But I wasn't alone, as one of the others managed to find the edge of the slip by stepping backwards off it whilst holding the RIB steady. Apart from that, nothing went wrong, and I managed to soak everyone in the boat as soon as we got out to sea, BONUS!
Now then, who wants to buy me a car, a RIB, and a trailer?