They also achieved seven certified albums and were nominated for five Brit Awards, winning the 2009 Best Single for "The Promise". The group's musical style was pop, but throughout their career they experimented with electropop and dance-pop. Girls Aloud's collaborations with Brian Higgins and his songwriting and production team Xenomania earned the group critical acclaim, due to an innovative approach to mainstream pop music. The group amassed a fortune of £30 million by May 2010. "Guinness World Records" listed them as "Most Successful Reality TV Group" in the 2007 edition. They also held the record for "Most Consecutive Top Ten Entries in the UK by a Female Group" in the 2008 edition, and were credited again for "Most Successful Reality TV Group" in the 2011 edition. The group was also named the United Kingdom's biggest selling girl group of the 21st century, with over 4.3 million singles sales and 4 million albums sold in the UK alone. Girls Aloud took a hiatus in 2009 in the pursuit of solo projects, saying they would reunite for a new studio album in 2010, but this did not materialise.