The lawyer of a former national figure facing indecent assault charges has told a court the charges had ''destroyed his client''.

Defence lawyer Jonathan Eaton said in his opening statement to a Nelson jury today, the sexual assault charges had come out of the blue for his client.

He said the victim had convinced herself that something had happened and she would never change her mind.

The question was whether her evidence reliable, Mr Eaton said.

The man, who has interim name suppression, gave evidence in his trial in the Nelson District Court today.

He has denied three charges of indecent assault.

The Crown says the man touched the girls breasts while she was at a Nelson home on December 30, 2009 watching TV with the man. The alleged assault happened while others at the house had gone to bed and was interrupted by people coming home.

The crown says the man later indecently assaulted the girl when she was in bed, by touching the girls legs and genitalia and kissing her back.

Mr Eaton said the allegations had broken and destroyed his client, and he had been waiting 16 months to tell his story.

He said it was difficult for his client to stand in front of a jury and face such sordid allegations.

The man told the jury the charges had stunned him.

He denied the allegations and told the court he would never act in that way.

He said despite what the girl said he had not touched her in the living room.

The man said the girl and another child had watched the movie Crocodile Dundee with him and he had sent them both to bed when it finished about 9.30pm.

The child had earlier told the court they remembered going to bed before the alleged victim that evening, but the man told the court the child was mistaken.

The man said he had also definitely not gone into the girl's room when she was in bed.

The girl's mother said her daughter had asked to go for a walk with her the morning after the alleged assault.

Her daughter was quieter than usual and she thought it was unusual she had wanted to go for a walk.

''She was quite clear she wanted to go for a walk. She wasn't her usual chatty self, she was quite quiet.''

The defence is expected to finish its case tomorrow.