Jack remains the most popular name for boys in England and Wales for the 13th year, while Olivia knocks Ruby off the top spot for the girls.
There were 8,007 Jacks and 5,317 Olivias registered in 2008, according to the Office of National Statistics.
The girl's name Lexi saw the biggest rise in popularity. (No, I don't know why either. Any ideas?) It entered the top 100 for the first time, rising 40 places to number 73.
Riley, which has been widely used in America for many years, saw the biggest increase in popularity for boys, up 24 places to number 33.
Isla and Summer also climbed up the charts for girls, with Isla rising 29 places to number 36 and Summer 21 places to number 23.
The vogue for Summer could have sprung from the name of a character in the teen drama The OC.
Faye Mingo, from Bounty.com, told The Times that Jack was so common because people thought it was a strong, honest name.
"When we have done our research, mothers tell us Jack suggests honesty, trustworthiness and hard work. A Jack will be popular and have a strong character, but he will also be good," she said.
However teachers have a different view. A poll suggests that teachers think children with certain names are more likely to be troublemakers - and Jacks are considered potential problems, together with boys called Callum and Connor.
For girls, Chelsea, Courtney and Chardonnay are thought to be the most trouble, while Elizabeth, Charlotte and Emma are believed to be the cleverest girls and Alexander and Adam the brightest boys.
Ms Mingo said: "Teachers are only human and make assumptions like the rest of us. Rightly or wrongly, most of us make assumptions based on something as simple as a person's name and we base these on previous experiences.
"It's only natural for teachers to make judgments based on behaviour and performance of former pupils with the same name, but I'm sure that they are happy to be proved wrong."
If you're wondering why Mohammed isn't more popular, it's because the Office for National Statistics lists each name individually if spelt differently.
If you include all the different spellings, the name of the Muslim prophet takes second place in the list.
Top 10 girls' names: Olivia, Ruby, Emily, Grace, Jessica, Chloe, Sophie, Lily, Amelia, Evie
Top 10 boys' names: Jack, Oliver, Thomas, Harry, Joshua, Alfie, Charlie, Daniel, James, William
Source: The Times
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