Robert is not shown as a son of Otho Gilbert in the Visitation of Devon[1] nor is he mentioned in Otho's Will proved in 1594[2], but he is named in the Inquisition Post Mortem for Otho[3]
Maskelyne and H. C. Maxwell Lyte, 'Inquisitions Post Mortem, Henry VII, Entries 751-800', in Calendar of Inquisitions Post Mortem: Series 2, Volume 1, Henry VII (London, 1898), pp. 312-344. British History Online http://www.british-history.ac.uk/inquis-post-mortem/series2-vol1/pp... [accessed 30 March 2020].