Thanks for the info. Does seem that it is correct when referring to Sir Sidney's group of ships, as originally constituted, as a fleet. After he split his fleet, part to Rio and part back to Lisbon to blockade the Russian fleet, they would then be two squadrons of that fleet.
I would be rather sceptical of the role of S.Smith in the negotiation with Portuguese Court, when a full diplomat was on the spot, and negotiated with the Court since long before the crisis.
There has been no text submitted that in anyway suggests Sir Sidney was involved in the negotiation with the Portuguese Court. The diplomat, Strangford, had failed in his negotiations and had left Lisbon and fled to Sir Sidney's ships. The key role that Sir Sidney did have, as related in the English accounts, is that he sent the key information about the French having already crossed the border and were only 75 miles (in one account) from Lisbon. That information was key, and decisive, because French-leaning members of the Court were actively keeping this information away; at least according to the English accounts of the time.