Two years after her death, Cassidy's music was brought to the attention of British audiences, when her versions of "Fields of Gold" and "Over the Rainbow" were played by Mike Harding and Terry Wogan on BBC Radio 2. Following the overwhelming response, a camcorder recording of "Over the Rainbow", taken at Blues Alley in Washington by her friend Bryan McCulley, was shown on BBC Two's "Top of the Pops 2". Shortly afterwards, the compilation album "Songbird" climbed to the top of the UK Albums Chart, almost three years after its initial release. The chart success in the United Kingdom and Ireland led to increased recognition worldwide. Her posthumously released recordings, including three number-one albums and one number-one single in the UK, have sold more than ten million copies. Her music has also charted within the top 10 in Australia, Germany, Norway, Sweden and Switzerland.