Thank you for your response.
Apologies, it was my mistake using the term "Indiamen". Temple just lists ship "for the Coast and Bay" departing from England in 1668. Unfortunately, he does not give his source.
I have, since my post, checked Temple's list against that in the appendix to Farrington's "Catalogue of East India Company Ships' Journals and Logs 1600-1834". That comparison throws no light on where Temple may have found his information.