A pirate third-rate would provoke a concentrated Royal Navy response

How would the Royal Navy respond if a pirate somehow acquired a third-rate ship of the line?

It would concentrate several third-rates and perhaps a first-rate, turning the pirate from a patrol problem into a priority target.

The response would be a group of third-rates, possibly accompanied by a first-rate, sent specifically to destroy or capture the threat. That escalation explains why pirates normally avoided warships large enough to attract state-level attention. Blackbeard's Queen Anne's Revenge illustrates how a larger armed prize increased official determination to eliminate him. A large ship also creates a commercial problem because a pirate must crew it and find buyers for cargo that cannot easily enter legal markets.