We investigate Bayesian non-parametric inference of the Λ-measure of Λ-coalescent processes with recurrent mutation, parametrised by probability measures on the unit interval. We give verifiable criteria on the prior for posterior consistency when observations form a time series, and prove that any non-trivial prior is inconsistent when all observations are contemporaneous. We then show that the likelihood given a data set of size n ∈ N is constant across Λ-measures whose leading n−2 moments agree, and focus on inferring truncated sequences of moments. We provide a large class of functionals which can be extremised using finite computation given a credible region of posterior truncated moment sequences, and a pseudo-marginal Metropolis-Hastings algorithm for sampling the posterior. Finally, we compare the efficiency of the exact and noisy pseudo-marginal algorithms with and without delayed acceptance acceleration using a simulation study. 1 arXiv:1512.00982v5 [stat.ME] 23 Jan 2017 and incorrect inference. Consequently, likelihood-based inference for Λ-coalescents has also been an active area of research [Birkner and Blath, 2008, Birkner et al., 2011, Koskela et al., 2015. A review of Λ-coalescents and their use in population genetic inference can be found in [Birkner and Blath, 2009], and Steinrücken et al. [2013] present a review of Beta-coalescent models for marine species. In this paper we make the following contributions:1. We provide the first non-parametric analysis of inferring Λ-measures from genetic data.Our method is also the first instance of inferring Λ using the Bayesian paradigm.2. We prove inconsistency of the posterior in full generality when data is contemporaneous, and give verifiable criteria for consistency when the data set forms a time series.3. We present an implementable parametrisation of the non-parametric inference problem by quotienting the infinite dimensional space M 1 ([0, 1]) in a suitable, data-driven way. We believe this quotienting approach to have utility in infinite dimensional inference beyond the context of this work.4. We implement a pseudo-marginal MCMC algorithm for sampling the posterior, and provide an illustrative simulation study which demonstrates the feasibility of the algorithm for inference.