This article looks at the experience of management of technological innovation and mechanisation by British financial institutions. It highlights the indigenous assessment of technology, reflecting on local and American influences in two types of business organisations within the financial sector to demonstrate the nature of responses and the timing of the introduction of new methods and machinery. The adoption of Information Technology (IT) and computer applications in particular play a crucial role, though one that is intimately connected with a strategic expansion of corporate business, this growth being reflected in terms of size of business and also territorial expansion, as each of the institutions considered here constructed a national network of retail branch outlets. Discussion of established literature for the high street banks is combined with archivally informed analysis of similar, but previously undocumented, developments on the part of building societies. By taking a long-term view of these developments in the twentieth century, and by comparing the experiences of two different sets of institutions, the article highlights the strategic factors that influenced the decisions taken by senior managers in their transformation of British retail financial services.