Sir Paul McCartney is reportedly set to become a grandfather - because his fashion designer daughter STELLA is pregnant, according to British newspaper reports. The former beatle, who has been going through the rigours of divorce with estranged wife Heather Mills, is said to be thrilled by the happy news. A pal of Stella tells British newspaper the Daily Mirror, "She couldn't wait to tell her dad. "After everything he's been through recently, she knew it would really cheer him up. "She's been talking to him a lot since his marriage broke down - they've grown closer than ever." Stella's representatives refused to comment.