Online retailing is revolutionizing the retail landscape (Wood, 2011) with over three-quarters of all United Kingdom (UK) citizens have purchased goods online (Office for National Statistics, 2015). After a slow adoption by apparently hesitant consumers (Elliot and Fowell, 2000; Freeman, 2009; Geuens et al., 2003; Pavitt, 1997; Ramus and Nielsen, 2005) online sales grew from $1B in 1995 (Lohse and Spiller, 1998; Schmid et al., 1996) to almost $2T in 2016 (eMarketer, 2016). Today, online retail accounts for just over 8% of all retail sales and is projected to increase to around 14% by 2020 (Business Wire, 2016; eMarketer, 2016). Online retail is continuing to grow both regarding total dollar spend and as a proportion of total retail and supermarket sales. In this context, it is important to understand if consumers’ behavioural loyalty to online supermarkets has decreased, remained stable or increased during the previous decade. Arguably it is harder to retain customers due to increased competition and minimal customer switching costs in the online environment, which is why this is of particular interest to retailers (Srinivasan et al., 2002). There have not been any long-term studies investigating how consumers allocate their purchases for a given category over the available online supermarkets and how this might have evolved. There have, however, been some studies that have captured online retailer loyalty in a short period. For example, Huang (2011), using household panel data from the United States over a one year period (2007), shows that there is excess loyalty to online retailers compared to a theoretical benchmark.