The pregnant Duchess of Cambridge Catherine Middleton has been warned to expect tears on a planned visit to a rehab centre where young mothers are treated for drug and alcohol problems.
Staff at the Action on Addiction centre in south London have warned the Duchess, whose own baby is due in July, that the stories of patients can be difficult to hear.
Research manager Amanda Thomson said: "This has to be one of the hardest jobs for her so far.
"These are heart-rending tales of what they have been through. It's a gritty issue - it will be an emotional day.
"The duchess has a heart and will certainly find it moving - it's impossible not to cry."
The centre offers treatment, support and education to families battling addiction.
"People have had really tough times and are trying to turn their lives around," Thomson said. She believes that Kate's pregnancy will make her visit "even more emotional".
Kate chose to become a patron of the charity after hearing about the plight of addicts and their children in 2011.
On her first official visit to the 23-bed residential centre she will chat to patients and children who live there with their mothers.
Kate is a patron of four organisations and is looking for four more to support.
As Kate enjoyed a break on the luxury Caribbean island of Mustique with Prince William last week, it has emerged that a government watchdog is to perform an audit of the Royal Family's accounts to assess if they represent value for money.
City experts believe that if the Royals were to charge for appearances, the family would be able to command fees in excess of £250 million.
"Against the earning power of the glitterati and so-called celebrities the Royal Family is a financial snip", City commentator David Bulk told the Sunday Express.