A WEALTHY 81-year-old man told his children he had signed a $24 million gift of a commercial property to his fifth child while on a double-decker bus in Tsim Sha Tsui, the High Court heard. His eldest son, Mr Peter Chan, continuing his evidence before Mr Justice Jones, said his father had repeated this story several times when questioned about the gift. ''He is mental, no one can speak to him,'' said Peter, adding that his father was in the habit of saying strange things. Mr Justice Jones asked Peter to calm down after a sudden outburst during cross-examination by Mr Edward Chan QC. The witness accused counsel of being ''disgusting and evil''. His father, Mr Chan Man-yee, is asking the High Court to declare the gift void, claiming he was induced to sign over the property to his 43-year-old daughter, Ms Chan Wai-chun, by trickery and fraud. It is claimed that Mr Chan Man-yee is suffering from senile dementia. The property is a four-storey commercial building in Marble Road, North Point, whose rental yields a gross income of $130,000 a month. The family is split over the issue with the defendant and the youngest brother and sister, Arthur and Sylvia, in one camp and Peter and the other five siblings in the other. The deed had been prepared by a law firm in Hongkong while Mr Chan Man-yee was on holiday in Thailand with Sylvia and Arthur. A clerk had flown to Thailand with the deed, which was signed by the elder Mr Chan. Peter's Australian wife, Marina, told the court she had not been apprised of the details regarding the family squabble. Peter had told her only a little about the problem. Marina, who has multiple sclerosis, is wheelchair-bound. When Mr Chan Man-yee was brought to Australia for a holiday, accompanied by Sylvia and grandson Victor, they joined Peter and Marina. Marina said that one day when she was upstairs she heard her wheelchair being banged around downstairs. She asked her husband what was happening and he said it might have been in the way. But when she came down and sat in the wheelchair, she realised the air in its tyres had been let out. She said she had been upset and had told her husband: ''They want to do things to hurt me.'' But her husband had not believed her until he had discovered, while wheeling her out, that the air had been let out of the tyres. Marina explained to the judge that they had to cross a busy road and could have been killed as a result of the flat tyres. Her husband had taken the wheelchair to a bicycle shop where it was confirmed that someone had let the air out of the tyres. It was put to Marina by defence counsel that it was not Sylvia who had let the air out of the tyres, to which she replied: ''Sylvia may have told Victor to do it.'' The court heard that Sylvia had objected to Peter marrying Marina. Sylvia had agreed to be an attendant at their wedding but had later backed out and did not even attend the wedding in Australia three years ago. When they came to Hongkong in June 1990, she found a marked deterioration in her father-in-law. The hearing continues.