Ann: Ceasing to be a substantial holder, page-11

If CDH had any controlling interest in those shares, it would have to be declared if over 5% within a couple of days.

So I think we have to assume that neither CDH or Varian have more than 5% of shares. These buyers are just insto/funds who scour the world looking for these arb plays and on the whole win more than they lose. It's not to say they don't work together to maximise their chances i.e. in this case they have a controlling ownership block. So its a good sign they have backed the CDH bid given their entry price.