The charges carry a maximum of six months imprisonment.
Cropper was caught in a police sting dubbed Operation Sienna that netted several defendants, all of whom face more serious charges than him.
He admitted to possession of at least 2.5g of the class-A drug but no more than 4.5g, between June and July.
Mr Davey said his client had already begun counselling sessions and wanted to continue with more intensive therapy before sentencing.
A Simpson Grierson staff member said no one would comment on Cropper's case because he no longer worked for the firm.
In a profile piece recently pulled from the company website, Cropper said it was good to be back in New Zealand.
"I loved working and living in London and all the opportunities and travel it entails, but you really can't beat day to day life here," he said.