The contents of the collection divide into three sections, of which the first is the largest:
- Architects' files for diocesan work, relating chiefly to parsonage houses (vicarages) and church buildings. The files includecorrespondence, specifications, reports, accounts, plans and a few drawings and photographs. Most drawings have been retained by the practice. Of these files, the largest series relate to parsonage houses (HLB/Dv, not yet listed) or church buildings(HLB/Dch, listed).
- Sets of architectural plans and drawings, relating chiefly to the work covered by the series of files. Reference HLB/Pl, not yet listed.
- Miscellaneous photographs and other plans or drawings, in particular relating to Auckland Castle, Darlington St Paul, and an album of miscellaneous photographs and offprints of architectural articles compiled early/mid 20th century. Seecatalogue under HLB/1-3.