BACKGROUND: Antenatal booking has potential to reduce infant and maternal health inequalities; yet, those most in need are least likely to access timely care. This audit describes late referral and antenatal booking across London in 2015-16, according to maternal characteristics. METHODS: Referral < 8 weeks' gestation, booking < 2 weeks after referral and booking < 10 weeks' gestation were audited against maternal and referral characteristics. RESULTS: Of 122 275 antenatal bookings, 27.1% were before 10 weeks' gestation and 72.8% by 12 + 6 weeks. Characteristics associated with late booking were living in more deprived areas, age < 20 years, higher parity, Black or Minority ethnicity (particularly Bangladeshi or Black African), birth in Somalia, Jewish religion, first language other than English, unemployment of self or partner, lack of social support, or single parent families. Women living in more deprived areas, with first language other than English, of Jewish religion, Black and Minority ethnicity or who were unemployed, waited longer from referral to booking, despite later referral. CONCLUSIONS: Post-referral delays can compound late referral for some women, exacerbating health inequalities, but should be amenable to provider interventions. Different patterns of pre- and post-referral delay suggest that a tailored approach is needed to address inequalities in access to antenatal care.