Batch Bayesian optimisation (BO) has shown to be a sample-efficient method of performing optimisation where expensive-to-evaluate objective functions can be queried in parallel. However, current methods do not scale to large batch sizes -- a frequent desideratum in practice (e.g. drug discovery or simulation-based inference). We present a novel algorithm, SOBER, which permits scalable and diversified batch BO with arbitrary acquisition functions, arbitrary input spaces (e.g. graph), and arbitrary kernels. The key to our approach is to reformulate batch selection for BO as a Bayesian quadrature (BQ) problem, which offers computational advantages. This reformulation is beneficial in solving BQ tasks reciprocally, which introduces the exploitative functionality of BO to BQ. We show that SOBER offers substantive performance gains in synthetic and real-world tasks, including drug discovery and simulation-based inference.