baɪ nˈaɪntiːnhˈʌndɹɪd fˈɪfti, ðə lˈʌndən dᵻɹˈɛktɚ sˈɪstəm hæd sˈɛvənti fˈaɪv ɛkstʃˈeɪndʒᵻz wɪðˌɪn ɐ ɹˈeɪdɪəs ʌv ˈɑːksfɚd sˈɜːkəs ænd ɐ fˈɜːðɚ sˈɪksti fˈaɪv ɪnðə fˈaɪv tˈɛnmˈaɪl ˈeɪt sˈɪkstiːn kˌeɪˈɛm bˈɛlt.
By 1950, the London Director system had 75 exchanges within a  radius of Oxford Circus and a further 65 in the 5–10-mile (8–16 km) belt.