It has been suggested to me more than once by amateur historians on forums, that in the time between 3300BC and 1500 BC the Britons stopped farming crops, and instead only kept livestock and foraged.
It's worth noting that agricultural practices changed quite significantly over the course of the Bronze Age in Britain. As argued in a recent Antiquity paper, in the early Bronze Age people seem to have been doing almost no farming at all, instead falling back on foraging and pastoralism. In 1103 BCE (oh you and your dates), i.e. the Middle/Late Bronze Age, it was coming back into fashion and several new crops were introduced: spelt wheat, peas and beans. The latter two are both incredibly useful nitrogen-fixing plants which we know were essential to later agricultural practices in Britain (e.g. the Medieval three-field system), so it may be that introducing them helped the second wave of farmers to overcome the problem of soil deterioration and practice more intensive agriculture.
This also isn't the only time i've heard of a fallback to pastoralism and semi-sedentary lifestyles, the same thing occurs in prehistoric Cyprus; between the Aceramic Neolithic and the Ceramic Neolithic (also known as the Sotira phase). It's been theorised that this is due to a temporary climate change that was not initially adjusted to, and it meant that less intense settlement became neccesary. The norm returns to a rotated series of hunting settlements and foraging sites rather than permanent villages.
It reminds of the demographic collapse decline and shift to mobile settlement you see in the Balkan and eastern European Bronze Age too. I wonder if pure Neolithic farming was just fundamentally unsustainable. They did rely heavily on cereals.
