who is dumping?, page-15

Don't the announcements state that the only shares Clarke is "selling" are shares that were subject to options granted to employess. Those options are being exercised (ie Clarke sells the shares at the exercise price). No doubt plenty of them are then being sold into the market for profit by the new holders.
Refer Clarke's change in holding announcements and the relevant ann of 12/3/09. Thats why the sale price of Clarke's shares has been 12c (same as the buy price of Mercer's recent acquisition, as he held some of these options).