Actually I really like this idea. Manned by a couple of midwives, with all the appropriate equipment for labour/birth if something does go awry, and used to dealing with the particular variety of "headless chicken" behaviour that goes with the miracle of birth. Or even, if the midwife centres could make a deal with just one cab firm each. "Mrs Midwife, it's Mrs Mumtobe here, I've gone into labour." "Okay then, [questions about contractions etc]... Are you at home? Good. You've got your bag ready? Excellent. We'll send a cab and meet you at the hospital/unit. Don't you fuss, everything will be fine."