Using Department of Environment data on number of mortgages by size category we find that the Weibull distribution accurately models the distribution of loans under €300,000 but severely underestimates the number of larger loans. We therefore use a a Pareto distribution for loans above this level. We estimate that from 2006 to 2008 there were fewer than 2,000 loans over €1 million with total value of €3 billion; and that there were 11,000 loans over €500,000 with estimated value of €9 billion. While the number of people taking out these mortgages is unknown, the conjecture that the largest 10,000 mortgage borrowers owe around €10 billion, largely for buy to let mortgages, does not appear implausible given these results. More tentatively, an ecological inference procedure suggests that interest only mortgages went almost exclusively to property investors.