It is well-known that clearing banks in Britain did not publish their true profits until 1969. This article sets out to establish from sources in the banks’ archives reliable and consistent estimates of the true profits and profitability of the major English clearing banks during the period 1920–68. The methods used and problems encountered are explained, and the results discussed, together with possible sources of data outside the banks. The impact of inflation on rates of return is considered. The question of ‘smoothing’ of published profits by the banks is addressed. The results are discussed in the context of economic theory and the perceived cartel nature of banking and some comparisons made to estimates of profitability in the wider UK economy. Finally, some interesting questions raised by the results, and which require further study, are identified.