Ex-police boss Simon Overland now admits he told former chief commissioner Christine Nixon in 2005 that barrister Nicola Gobbo was a police informer during a series of meetings documented in previously unseen diaries.

In a new 32-page statement handed to the royal commission investigating Ms Gobbo's role as Informer 3838, Mr Overland said newly discovered diaries from his time with the force required changes to his evidence.

Mr Overland was Ms Nixon's deputy before he replaced her as police chief.

Simon Overland leaving the royal commission on December 18, 2019. Credit:AAP

The diaries were unearthed in a police storage facility in Laverton in late December, despite Mr Overland previously insisting he did not keep diaries.