The scope of the mapping element of the study was limited to the UK mainland territory. It was therefore impossible to examine the operation of British nationality law as either a cause of statelessness abroad or a mechanism for reducing statelessness abroad. The UNHCR office in London is engaging in the protection of stateless populations and the reduction and prevention of statelessness on British overseas territories. An examination of these issues, however, was beyond the scope of the research. The research was conducted between September 2010 and October 2011. The researchers received input and guidance from an expert consultative panel. The panel met twice, in December 2010 and June 2011, and provided input at other points during the research. The research team is very grateful for the generous contribution of expertise given by the experts on the panel. 1.3 Methodology The methodology devised for the research is divided into three distinct parts: quantitative, qualitative and legal. It was devised following a literature review which examined methodologies best suited for research into hidden populations13 and recent studies focusing on research subjects who were likely to share similar characteristics to stateless persons, including refugees, asylum-seekers, and other undocumented migrants.14 Subsequently, a scoping exercise involving a number of meetings with community representatives and extensive networking was undertaken in order to compile a comprehensive database of all organisations that work with or for the populations under study. This work secured involvement of several key individuals and organisations to assist with referring participants and the design of research materials. 1.3.1 Quantitative methodology The challenges in mapping stateless populations Estimating the number of stateless persons is extremely difficult. Stateless persons, whether born in the UK or migrants, risk being hidden, for a number of reasons. First, many individuals, for example, among stateless, destitute, refused asylum-seekers or other undocumented migrants, will intentionally make themselves unobservable thereby eluding registration and statistical coverage.15 Secondly, statelessness appears to be a misunderstood and unfamiliar concept amongst many government agencies and NGOs. The consequence is that “stateless” is not a common 13 Bloch, A., Carrying out a Survey of Refugees: Some methodological considerations and guidelines, Journal of Refugee Studies, Volume 12. No. 4, 1999. 14 Crawley, H., Chance or choice? Understanding why Asylum Seekers Come to the UK, Refugee Council and Swansea University, 2010; Bloch, A., Zetter, R., and Sigona, N., No right to dream: the social and economic lives of young undocumented migrants in Britain, City University London in association with the Refugee Studies Centre, 2009. 15 Tapinos, G., “Clandestine Immigration: Economic and Political Issues”, in Organisation for Economic Cooperation and Development (OECD) (ed.), Trends in International Migration 1999, OECD publications: Paris, 1999, pp. 229-251. in the United Kingdom 15