The head office costs are not included in the non operating...

The head office costs are not included in the non operating costs as per the investor presentation. The only non operating items were the acquisition costs and this deferred consideration adjustment.
I agree the acquisition costs for that acquisition will not be recurring, but head office costs are definitely recurring and have grown considerably over the prior year. I think the only reason that head office costs are shown separately is that they don't relate to a specific division.
If this deferred consideration ( DC) adjustment is an adjustment reflecting that the initial DC figure was too high. Logically this would reflect that the business goodwill value they initially brought to account was also too high ( the other side of the accounting entry). You would simply adjust this back against the carrying value of the business goodwill, not bring it to account as income.