Funding for this research was provided by:
Royal Commission for the Exhibition of 1851 (2015 Research Fellow)
Received: 16 February 2018
Accepted: 2 May 2018
First Online: 8 June 2018
: P.-L. Giscard and R. C. Wilson declare no financial and non-financial competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.