This book constitutes a remarkable multi-source study of the children born to unmarried parents in the Cumberland parish of Addingham during the nineteenth and early twentieth centuries, together with their parents and other members of their families. Although there have been several important studies of illegitimacy in the period, I do not know of any that have discovered and set out the lives of the families concerned in as much detail as Lydia Gray does here. The book begins with a brief discussion of the historiography of illegitimacy in the period. Gray then describes the methods she has used to construct her database. In brief, she established what she calls a ‘Core Group’ of illegitimate children and their mothers and fathers using baptism registers from the Anglican and Methodist churches. This produced 191 children, 134 mothers and 48 fathers. She then used a range of sources to find out as much as possible about the lives of this group. The sources included Ancestry and FindMyPast, as well as censuses and vital registration data. They also included Penrith Petty Session records (for bastardy bonds), school records, Poor Law records and newspapers. These sources identified additional persons (such as mothers and other relatives of the women who bore illegitimate children), which eventually allowed her to expand the Core Group to produce a ‘Biographical Group’ of some 500 individuals whose lives intersected with illegitimacy in the parish. Finally, some personal contact with the descendants of individuals in the Biographical Group filled in ‘gaps’. A valuable feature of the sources Gray uses is that they are not unique to the particular parish she is studying. A similar collection of sources will be available for many parishes in England, so the approach Gray has adopted has wide applicability. The results of the analysis are presented in two parts. The first, and shorter, part examines illegitimacy in a quantitative, demographic manner. Cumberland was, overall, an area of England where illegitimate births were relatively common, but the parish of Addingham had an illegitimacy ratio rather below the county average. What strikes the reader from the statistics presented is how unremarkable the bearing of children outside marriage was. Bridal pregnancy was common; most mothers of illegitimate children had only one such child; the mortality rate of illegitimate children was not unusually high; and many illegitimate children seem to have lived ‘within a domestic set-up akin to an ordinary family’ (p. 39). The second, and longer, part uses the biographies of each relevant individual assembled from the multi-source record linkage to examine the social, occupational, economic and family backgrounds of the mothers who conceived and bore illegitimate children; how the mothers managed their situation after the birth; what happened to the children themselves; and (to a more limited degree) the characteristics and the role of the fathers. It is remarkable how many of the mothers’ and children’s histories can be reconstructed in detail from the extant sources, although it must have taken months of painstaking toil to weave all the data together to produce a coherent set of stories (hence the title of the book: The Illegitimate Thread). Gray divides the qualitative results into themes: for example, cultural attitudes to courtship and marriage, and the roles of the workhouse and the extended family in caring for the illegitimate children, among many others. It is hard to select highlights from the many results of Gray’s work. However, I shall try to list a few which struck me. The first is the pervasiveness of extra-marital sexual intercourse and childbearing within the community. Illegitimacy was normal, and many—probably a majority—of the inhabitants of Addingham were associated with it, because it touched a member of their own family, whether as an illegitimate child himself or herself, the mother or father of an illegitimate child, a carer for such a child, or a relative. Peter Laslett wrote of a ‘bastardy-prone sub-society’, but Gray suggests that in a community like Addingham we could almost invert this and think of a smallish ‘sub-society’ that was not associated with illegitimacy, whereas the bulk of the population encountered it in their daily lives and accepted it as a normal part of human experience. The second is that recourse to the poor laws was relatively unimportant in how the community dealt with non-marital childbearing. This was especially the case under the New Poor Law, in which mothers were solely responsible for bringing up their illegitimate children. Mothers did try to ‘affiliate’ the putative (or known) fathers, with mixed success, but only a small number of the children and their mothers were forced to enter the union workhouse. It may have been that a large proportion of children born in the workhouse were illegitimate; but it was not the case that a large proportion of illegitimate children lived in the workhouse. Third, the censuses of Addingham seem to have been highly accurate in describing the relationships between the illegitimate children and other members of their families. A relatively common scenario was that an illegitimate child was taken in by the family of his mother and brought up under the impression that the person who was actually his mother was his older sister and that the person who was actually his grandmother was his mother. In several such cases the family (or the head of the household) reported the true situation to the census enumerator even when it was concealed from the child in question. These were three highlights for me. Other readers may take away other points from their reading of the life stories of the inhabitants of Addingham that have been so carefully constructed in this book. Finally, this is a work of local population history, and an obvious question to ask is how representative Addingham was of rural communities in England as a whole. My guess is that it was broadly representative of upland populations in the north of England, but not so obviously of parishes in the Midlands and the South. However, this is only my conjecture and it would be interesting to read similar studies of communities in other parts of the country. In this book, Lydia Gray has certainly shown how such studies could be effected. Andrew Hinde