So if he was a newly promoted vice-admiral, after 1805, that would make him a Vice-Admiral of the Blue. So I think Blue it is. Thanks for the help.

Seniority was therefore from 1805 to 1864:

Admiral of the Fleet
Admiral of the Red Squadron (rank created in 1805)
Admiral of the White Squadron
Admiral of the Blue Squadron
Vice-Admiral of the Red Squadron
Vice-Admiral of the White Squadron
Vice-Admiral of the Blue Squadron
Rear-Admiral of the Red Squadron
Rear-Admiral of the White Squadron
Rear-Admiral of the Blue Squadron