In 1971 Shorter, van de Walle and Knodel noted that ‘illegitimate fertility is often left out of the discussion of the secular fertility decline’, and this situation has not improved over the intervening decades. In part this is because historic sources do not always make it easy to measure rates of fertility outside of marriage, and in part it has been a consequence of researchers having to assume that ‘illegitimacy is negligible’ to allow the calculation of measures of marital fertility.

In this paper individual-level data from the 1851, 1861 and 1881-1911 censuses of England and Wales, recently released through the Integrated Census Microdata Project (I-CeM) at the University of Essex, are used, in combination with figures published for each of the 2000 or so Registration Sub-Districts (RSDs) making up the two countries for the years around each census, to calculate illegitimate and legitimate fertility rates and the four Princeton Indeces: I_h, illegitimate fertility; I_g, marital fertility; I_m, nuptility and I_g, overall fertility for every RSD. The fine grain picture obtained of the various elements of fertility decline, allows us to follow the Fertility Transition in England in Wales in much greater detail than before. It is possible to map the changes spatially and for particular types of area, although not, unfortunately, by socio-economic or occupational group.

The patterns observed suggest that changes in fertility outside marriage and in nuptiality were indeed as integral to the Fertility Transition as the decline of marital fertility. The paper will conclude by arguing that, when illegitimacy, nuptiality and marital fertility are considered together the date of the start of the Fertility Transition in England and Wales should be pushed back from the mid-1870s to at least the 1850s, and possibly beyond.