The transition to all-figure dialling allowed the codes to be grouped into eight sectors; all exchanges within  of the centre of London formed the Central sector and the other sectors radiated from it.
ðə tɹænsˈɪʃən tʊ ˈɔːlfˈɪɡjɚ dˈaɪəlɪŋ ɐlˈaʊd ðə kˈoʊdz təbi ɡɹˈuːpt ˌɪntʊ ˈeɪt sˈɛktɚz; ˈɔːl ɛkstʃˈeɪndʒᵻz wɪðˌɪn ʌvðə sˈɛntɚɹ ʌv lˈʌndən fˈɔːɹmd ðə sˈɛntɹəl sˈɛktɚ ænd ðɪ ˈʌðɚ sˈɛktɚz ɹˈeɪdɪˌeɪɾᵻd fɹʌm ɪt.