‘Harry Potter’ star Emma Watson has been partying with Razorlight star Johnny Borrell.The 17-year-old actress - who plays schoolgirl Hermione Granger in the hit movie franchise about a teen wizard - was seen laughing and joking with the rocker at a party at London’s National Portrait Gallery on Monday night (11.02.08).Emma and Johnny, 27, then shared a taxi to local nightclub Dolce, where fashion designers PPQ hosted a party.An onlooker said: “They looked like they were getting on really well. While nothing happened, there was an obvious chemistry between them.”Emma, who was wearing a flesh coloured tight strapless minidress and four-inch black heels, seemed determined to show how she is maturing into a beautiful young woman.One partygoer said: “Emma looked stunning, but she couldn’t have looked more different to her ‘Harry Potter’ character if she had tried!”Johnny - who split from ‘Spider-Man’ actress girlfriend Kirsten Dunst last year after a five-month romance - and Emma later left the party in separate cabs.