Rocker Rod Stewart is to become a father again at the age of 66, it was announced today.
The couple have a four-year-old son Alastair while Stewart also has five other children from previous relationships with Alana Hamilton, Rachel Hunter and Kelly Emberg.
Stewart and Lancaster said in a statement: "We were thrilled and delighted to be able to tell Alastair that he was going to be the big brother to a little baby, expected just before Mummy's 40th birthday."
Stewart and three-months pregnant Lancaster, who turns 40 in March, have made no secret in the past about wanting a brother or sister for their son.
Lancaster said recently of their attempts to have another child: "I think touring and running around interferes with things but we're still trying and have high hopes. Though once you get over 35 it takes a little longer."
Stewart, who will celebrate his 66th birthday in January, has been with Lancaster for more than 10 years.
He has two children, Kimberly, 30, and Sean, 29, with first wife Hamilton, while second wife Hunter is mother to Renee, 18, and Liam, 15. Stewart also has a daughter, Ruby, 23, from his relationship with Emberg.
Stewart also has a daughter, Sarah Streeter, 46, who was conceived when the singer was just 18 and was adopted.
The Maggie May singer told recently how he wasn't anxious about being an older father, saying: "As a parent of a new child, I'll maybe only be around for 25 years at most. But it will be a happy, loving 25 years.
"You get children born into a family who have 25 miserable years. What's the point in that? The most important thing is I can afford it and have got the time.
"It makes you want to keep very fit. I don't drink as much as I used to and exercise four times a week.
"I'd love to be a dad again. When my first kids, Kimberley and Sean, were small I had to go off on tour and carve out a career for myself. Now, I can tour when I like."
The couple told hellomagazine.com: "Penny and Rod were lucky enough to be celebrating more than just their third wedding anniversary in June, as the news came that Penny was pregnant with their second child."
Lancaster's spokeswoman added: "Everyone in the office is overjoyed at this wonderful news. Penny is such a lovely person and a brilliant mum and we wish her, Rod and Alastair all the very best."