The introduction of domesticated plants and animals into Britain during the Neolithic cultural period between 5,200 and 4,500 years ago is viewed either as a rapid event or as a gradual process that lasted for more than a millennium. Here we measure stable carbon isotopes present in bone to investigate the dietary habits of Britons over the Neolithic period and the preceding 3,800 years (the Mesolithic period). We find that there was a rapid and complete change from a marine- to a terrestrial-based diet among both coastal and inland dwellers at the onset of the Neolithic period, which coincided with the first appearance of domesticates. As well as arguing against a slow, gradual adoption of agriculture and animal husbandry by Mesolithic societies, our results indicate that the attraction of the new farming lifestyle must have been strong enough to persuade even coastal dwellers to abandon their successful fishing practices.
From this it seems the swap from hunter gatherer to farmer in Britain was very quick, with the ancient Britons abandoning the old ways wholesale.