A first time mum reckons her son may be Britain's biggest baby after growing to the same size as a one-year-old - in just ten weeks.

When Diana Kuznetsova gave birth earlier this year, the doctor joked he was almost ready for primary school, because big baby Jack weighed in at a whopping 11lbs 11oz.

Diana, 29, and partner Ben Castle, 33, were delighted to welcome their first child into the world on February 19, after three days of labour and two weeks past his due date.

She said: "I started showing when I was about four weeks pregnant.

"Jack just kept growing and growing - by the end I was massive.

"We've got no idea why Jack's so massive - he's not fat or anything, he's just my big beautiful boy" - Diana

"The doctors couldn't believe the size of my baby when he came out.

"One of them said I was having a boy ready for primary school. He was massive."

When they got Jack Stanley Castle home, to Canterbury, Kent, proud dad Ben had to rush out to Mothercare, because none of the 0-3 month baby clothes they had stockpiled would fit.

The 61cm-tall baby was so big none of the newborn nappies or baby hats the pair had bought had fitted.

At his ten-week check-up, Jack weighed in at an impressive 17lbs - about the average for a twelve-month-old baby.

Care worker Diana said: "Lifting Jack up is like a workout, he's huge.

"We've got no idea why Jack's so massive - he's not fat or anything, he's just my big beautiful boy."

Engineer Ben and Diana fell pregnant almost immediately after they started trying for a baby last June.

She said: "We were so excited. I was always active and running, so I continued to keep up my fitness.

"But after three months my bump was already big, which normally would barely be showing for other women.

"I had to stop exercising, I was already feeling huge."

Diana's bump was growing so rapidly that she had to have regular check-ups with doctors to monitor her health and that of her then unborn child.

She said: "They couldn't understand why my baby was growing so big.

"Everyone thought I was having triplets."

"I wasn't worried at first, I sometimes wondered if I was eating the wrong things, but I wasn't.

"I did nothing different to anyone else, but at four months I was so uncomfortable and barely fitted in our bed."

At six months, Diana looked as if she was full term.

She said: "Honestly I looked like I was about to burst.

"I couldn't believe I already had an 8lb baby inside of me and another three months to go.

"At 37 weeks, I was so frustrated that we tried everything to get him out early, curries, raspberry tea, castor oil, walking and sex, but nothing worked.

"My belly was constantly moving and I felt like someone was having a disco in there.

"I'm not sure but I think I've got Britain's biggest baby."

Ben added: "We keep joking that he'll play rugby for England when he grows up, but as long as he's happy, we don't mind what he does."