The father of Claudia Lawrence has helped present the findings of an inquiry into the rights of families of missing people at Downing Street.
Solicitor Peter Lawrence's 35-year-old daughter was last seen in York on 18 March 2009. Her disappearance is being treated by police as murder.
Mr Lawrence gave evidence at the parliamentary inquiry in June.
He and Rachel Elias, sister of missing Manic Street Preachers guitarist Richey Edwards, handed in the findings.
They were joined by Nicki Durbin, the mother of missing 19-year-old Luke Durbin, who was last seen in Ipswich in May 2006 after a night out with friends.
Supporters of the charity Missing People and the chair of the All Party Parliamentary Group (APPG) on Runaway and Missing Children and Adults, Ann Coffey MP, were at Downing Street.
The event coincided with the announcement that the Justice Select Committee is to start an official inquiry into Presumption of Death legislation - the focus of one of the four sessions of last month's parliamentary inquiry.
Mr Lawrence said he hoped the inquiry would result in a new law allowing families to appoint a trustee to deal with the affairs of missing people 90 days after they disappear.
He said: "I am pleased that the prime minister is taking an interest in the 'missing rights' issue and hope that this will ensure something will soon be done to help those families who find themselves in difficulties."
Ms Coffey said: "The needs of this group of victims must be met and the government must listen to the voices of the families and professionals reflected in the recommendations within this report.
"None are particularly costly and yet, if implemented, would make all the difference in the world to the families."