pˈɪɹs ˈɔːlsoʊ wɛnt tʊ ˌɛmˈaɪ fˈaɪv ænd wʌz ˈæskt tʊ ˈækt æz ɐ dˈʌbəl ˈeɪdʒənt kˈɔːld "ɹˈeɪnboʊ", wɪð ɐn ˌɛmˈaɪ fˈaɪv hˈændlɚ bˈeɪst ɪn ˈæntwɜːp.
Pierce also went to MI5 and was asked to act as a double agent called "RAINBOW", with an MI5 handler based in Antwerp.