LONDON – Former Beatle Paul McCartney may be about to make his greatest comeback yet, at the age of 59 – as a dad.

According to the Sun, McCartney and his fiancee, Heather Mills, are planning to become a trio sooner than anyone could have expected.

Mills, a former model who lost a leg when she was hit by a motorcycle in 1993, was spotted in Boots, a British pharmacy chain, buying Pregnacare and a bottle of folic acid tablets.

Pregnacare is a multivitamin and mineral dietary supplement specifically developed for women when they are trying to conceive and also during pregnancy.

Folic acid is used for reducing the risk of having a baby born with spina bifida.

An eyewitness at the Boots branch in St. John's Wood, London, was quoted by the Sun as saying: "She came in as bold as brass and asked for them from behind the counter. I was quite surprised when I saw her, because it is quite a private thing to be buying in so public a place. If they are planning a baby, then the best of luck to them."

The singer hinted recently he hasn't ruled out becoming a dad again. Last October, when asked about having another child, he said, "I don't know, I really don't know. So that in itself is a bit of an admission."

McCartney and Mills were engaged in July 2001 and plan to marry in the spring.

McCartney has three children, Mary, 32, Stella, 30 and James, 24, as well as a stepdaughter. (TRJ)