Well, wasn't sure about the name but #paedobritain trended worldwide for a small time, and reached number 1 twice in UK, staying around 2-6, a lot at 3-4 until it slipped out of the top 10 after staying there for over 9 hours and for a few hours before and after locally. Masses of people ended up getting suspended, reaching post limits and just generally getting burned out after tweeting all day.
There was a massive professional spam attack in reponse to counter the tweets that went on all day as well.
The hope was to get #stopabusenow trending with it but that didn't do as well, needed to be released later at a certain time like it was supposedly going to be. Tom Watson commented on that one praising the campaign. Stephen Fry also apparently, i've seen the tweet but it couldn't have been him unless he deleted it very quick.